# ramchand

Stuart Kovinsky posted a reply to Probability in the Problem Solving forum
“Many probability questions can be solved intuitively rather than with long calculations. Let''s try to do so with this problem! We can get off to a great start by flipping around the question: what''s the probability that Sally sits beside Andy? We know that it has to go BGBGBGBGB. We can ...”
December 31, 2013
Stuart Kovinsky posted a reply to Researchers in the Sentence Correction forum
“One more approach! The word "ancient" is a present use word - in other words, something is ancient from today''s perspective. Accordingly, if we''re talking about a present discovery, we don''t say "what appeared to be an ancient hunting ground"; instead, we say "what ...”
December 29, 2013
Stuart Kovinsky posted a reply to MGMAT Advanced Quant- Visual Ques. in the Problem Solving forum
“Hi Bharat! Let''s start by breaking down the info - there''s actually a lot more there than you may think! Possible scores are the integers 0 to 50, inclusive - that''s 51 possible scores. 100 people take the test. At most, 2 people can get the same score. Let''s assume for a moment that ...”
December 29, 2013
Stuart Kovinsky posted a reply to Skeletal Heat in the Critical Reasoning forum
“Hi Sid, you''ll find some decent free resources on the net, you just have to be really careful. I''d always look for reviews of the source before diving in and using its questions. For all you know, those free questions were written by some bored guy living in his mom''s basement! Depending ...”
December 29, 2013
Stuart Kovinsky posted a reply to Combinatorics: Solution Explanation in the Problem Solving forum
“Hi Dbloos! That answer is in fact correct. Here''s another way of looking at it: 2 out of the 14 patients will be chosen to receive P or R. Since the selection is random, each patient has a 2/14 chance of being one of the two. We can confirm this answer with common sense (a very powerful ...”
December 28, 2013
Stuart Kovinsky posted a reply to Samuel's Fishing Dilemma in the Critical Reasoning forum
“Hi Siddhu, a quick Google search reveals that this is yet another Platinum GMAT question, so it''s not surprising that it''s poorly constructed. The problem here is different - there are 3 valid weakeners among the choices. So, instead of no good answer (like the previous Platinum GMAT ...”
December 28, 2013
Stuart Kovinsky posted a reply to E-News Ads in the Critical Reasoning forum
“Hi Siddhu! This is another Platinum GMAT question - I''ve only seen 2 and I''m already super-unimpressed. There is no great weakener among the choices. For (C) to be relevant, we have to assume that "partners" means "people visiting one website will be faced with the same ...”
December 28, 2013
Stuart Kovinsky posted a reply to Skeletal Heat in the Critical Reasoning forum
“Hi Siddhu, please always post your sources. A quick search of the Oracle (i.e. Google) revealed that this a question from Platinum GMAT, of whom I''ve never before heard. This is a horrible question. None of the answers explain the paradox and, while a couple are classic traps, there is no ...”
December 28, 2013
Stuart Kovinsky posted a reply to Dice in the Problem Solving forum
“Hi Nipun! The problem with treating this like a permutations problem - which is when you''d simply do 6*5*4 - is that we don''t care about order, so you''re counting certain combinations multiple times. For example, the 3 dice could come up as a 5, a 4 and a 3. However, they could also come ...”
December 28, 2013
Stuart Kovinsky posted a reply to Quicker + alternate methods in the Problem Solving forum
“Hi! No such general formula exists - that pattern comes from an old GMAT question that gave you that summation as a rule to help you answer that one specific question. Whoever put it on a flashcard managed to confuse a whole bunch of people, though (which is why you should be very wary of ...”
December 28, 2013
Stuart Kovinsky posted a reply to tenth digit in decimal representation in the Data Sufficiency forum
“Hi! I''m assuming that this last part in quotes is your actually comment/question. It''s important to know the place names for the various digits in a numbers, so let''s do a quick review, using the example of: 12345.6789 We start numbering to the left and the right of the decimal place. ...”
December 28, 2013
Stuart Kovinsky posted a reply to MGMAT CAT Esteria vs Burdistan in the Critical Reasoning forum
“Hi Julls! This argument is a classic example of the most common pattern we see in critical reasoning: causation. In a causal argument, the evidence describes some phenomenon and the conclusion is the author''s explanation for that phenomenon. In every causal argument, the author makes 3 ...”
December 28, 2013
Stuart Kovinsky posted a reply to In the month of August, Pentheus Corporation made $200,000 in the Problem Solving forum “Not to derail a Magoosh post, but this one is actually solvable very quickly without backsolving or a calculator (although I''m generally a huge fan of backsolving!) as long as you know your common percent/fraction/decimal equivalences. First, we need the profit on that day: 1% of$200000 is ...”
December 27, 2013
Stuart Kovinsky posted a reply to Lanuguages in the Sentence Correction forum
“Hi! I''ve bolded the part of the sentence relevant to your question. Since we have "a language" in the non-underlined part, "within it" is correct. Also, it''s idiomatically correct to say "a dialect within a language", if that''s your main question. You could ...”
December 26, 2013
Stuart Kovinsky posted a reply to To find the total amount of water in 3 glasses in the Problem Solving forum
“Hi! Uva did a great job saying what you could do next, so I want to discuss what you could have done instead - everyone taking the GMAT should strive to follow the Lazy Test-taker Rule: Do the least amount of work possible to answer each question. On questions that ask you to find a range, ...”
December 26, 2013
Stuart Kovinsky posted a reply to Integer Properties in the Data Sufficiency forum
“I''m going to almost agree with Vipulgoyal, but say that the answer should be "C", together. Also, I''m assuming that the question was correctly transcribed and the "different" wasn''t omitted from "does m have more than 5 prime factors"? Since the Q stem omits ...”
December 24, 2013
Stuart Kovinsky posted a reply to To find the average speed in the Data Sufficiency forum
“Hi Sri! You''ve assumed that the car''s speed is constant - which is exactly what the question is designed to trick you into assuming! Remember: on the GMAT we only know what we''re explicitly told. Since we don''t know whether the car is travelling at a constant speed, there''s no way we ...”
December 24, 2013
Stuart Kovinsky posted a reply to Rate Problem in the Problem Solving forum
“Hi! You haven''t provided any answer choices, so I''m a bit confused - is this a problem solving or a data sufficiency question? You said that the OA is "6", but since we only have variables, how can the answer be an actual number? Your equation for time to catch up is dead on, ...”
December 24, 2013
Stuart Kovinsky posted a reply to Combinatorics.Plese help. in the Problem Solving forum
“All you''re really doing when you apply the "slot method" to these problem is using the combinations formula: nCk = n!/k!(n-k)! When order does NOT matter, that''s the formula we use. So, if we''re simply choosing 4 out of 7 and we don''t care about order, we get: 7C4 = 7!/4!3! ...”
December 23, 2013
Stuart Kovinsky posted a reply to What is the remainder? in the Data Sufficiency forum
“Hi Sri! For remainder questions, we often only need to look at the last 1 or 2 digits of the number. In this case, since we''re dividing by 5, only the last digit actually matters. So, we can recognize the pattern for powers of 2: 2^1 = 2 2^2 = 4 2^3 = 8 2^4 = ..6 2^5 = ..2 and so ...”
December 23, 2013
Stuart Kovinsky posted a reply to Need help on Percentage Question in the Problem Solving forum
“Hi Scraby! First, please always post the answer choices, since they play a large role in many GMAT strategies. On this question, for example, backsolving (working backwards from the choices) is almost certainly the quickest way to get the answer. Let''s approach it via both algebra and ...”
December 23, 2013
Stuart Kovinsky posted a reply to Most interns who work for pay hold positions... in the Sentence Correction forum
“Hi! This sentence is all about parallelism. When we have a list, we have to make sure that all the parts are stated correctly. When each part of the list has the same modifier, you can just put that modifier at the beginning of the list. However, when different parts require different ...”
December 23, 2013
Stuart Kovinsky posted a reply to What is the value of x - y ? in the Data Sufficiency forum
“Hi Sri! We know that both x and y are positive and that x is greater than y. We need to find an exact value for (x-y). 1) tells us that root(x) - root(y) = 1 If we square both sides, we get: (rootx - rooty)^2 = 1 x - 2root(xy) - y = 1 well, since have no clue what x and y are, ...”
December 23, 2013
Stuart Kovinsky posted a reply to Combinatorics.Plese help. in the Problem Solving forum
“When we''re counting we''re always dealing with whole numbers: for example, there are never going to be 3.5 possible groups. So, as soon as you get a fraction, you know there''s a problem. The problem with the using the "slot method" is that you''ve treated 2 different selections as ...”
December 23, 2013
Stuart Kovinsky posted a reply to Probabilit in the Problem Solving forum
“Hi! This may look like a probability question, but it''s really all about geometry. The question is really asking "what portion of ABCD is shaded?" This question is super quick if you use your graph-lined noteboard to draw the shape to scale - you''ll quickly see that the mini ...”
December 22, 2013
Stuart Kovinsky posted a reply to Probability Again in the Problem Solving forum
“Hi! This question is a great illustrator of the "one minus" approach to complicated probability problems. When you see "at least" or "at most" in probability, you''re going to be solving for multiple scenarios. However, it''s often quicker to solve for what you do ...”
December 22, 2013
Stuart Kovinsky posted a reply to Square Root of Variables in the Problem Solving forum
“No worries! It didn''t really affect your question or my response, I was just curious. Stuart”
December 22, 2013
Stuart Kovinsky posted a reply to Club members at least 35yrs old in the Data Sufficiency forum
“Hi! We only care about at least 35 vs below 35, so "children" are irrelevant. Q: how many members are 35 or older? We think: value question asking us to solve for an actual number, so we need info about numbers! 1) nothing about actual numbers (i.e. just a fraction) - ...”
December 22, 2013
Stuart Kovinsky posted a reply to Square Root of Variables in the Problem Solving forum
“Hi! First, the problem you posted doesn''t actually include a question, so I''m not sure for what you''re solving. In other words, you posted an equation, but no question. However, I can still answer your question - the official answer you posted and your answer are actually identical. We ...”
December 22, 2013
Stuart Kovinsky posted a reply to Bank fees in the Sentence Correction forum
“Hi Eric! This sentence is all about proper verb tenses - one of the most commonly tested issues in sentence correction. Remember to always use the non-underlined portion of the sentence (which is, by definition, correct) to guide your selection for the underlined portion. Here, as soon as ...”
December 21, 2013
Stuart Kovinsky posted a reply to Auto company profits in the Sentence Correction forum
“Hi Eric! Recognizing common GMAT idioms can help you cut to the heart of a SC question and ignore all the "fluff" that the GMAT includes to distract you. There are two important idioms to recognize in this argument. First, we "attribute to". However, since every ...”
December 21, 2013
Stuart Kovinsky posted a reply to Mall Occupancy in the Critical Reasoning forum
“Hi Lula! Anyone who wants to be a top scorer on the GMAT needs to learn to recognize common patterns. This argument exemplifies one such pattern in critical reasoning. It''s common for authors to identify a problem and then propose a solution. It''s also common for authors to go one step ...”
December 21, 2013
Stuart Kovinsky posted a reply to Number Line Data Sufficiency in the Data Sufficiency forum
“Hi! In geometry, whenever two points are put together like that, they always describe the line formed by connecting them. The same rule applies to number lines, which are really just a form of linear geometry.”
December 21, 2013
Stuart Kovinsky posted a reply to Please can you explain the reasoning behind this? in the Problem Solving forum
“Hi! We''re told that x is positive and increasing and we''re asked to determine which of 3 expressions will increase along with x. Here''s something to remember: the GMAT is not trying to be your friend, but it is trying to see how clever you are. So, we''re always using our cleverness to ...”
December 20, 2013
Stuart Kovinsky posted a reply to Pls explain the calculation in the Problem Solving forum
“Hi! This question is testing your ability to find limits and estimate. We''re told that K is the sum of the reciprocals of the integers 43 through 48, inclusive. In other words: K = 1/43 + 1/44 + 1/45 + 1/46 + 1/47 + 1/48 well, that''s a whole mess of ugly math, so there''s got to be a ...”
December 20, 2013
Stuart Kovinsky posted a reply to Data Sufficiency Qs in the Problem Solving forum
“Hi! What''s the source of this question? I''m asking because, technically, the 4 brothers could be quadruplets and all the same age. I really doubt that the question intends for that to be a possibility and the GMAT would never leave that ambiguity in place. Let''s assume that the question ...”
December 20, 2013
Stuart Kovinsky posted a reply to Pls help with the solution in the Problem Solving forum
“Hi! First, I''m not sure if the image I uploaded will work - for some reason the IMG uploader isn''t giving me any love! So, I''ve attached it as a document as well. In any case, let''s break the question down. We''re told that ABC are 3 points in the coordinate plane that do not form a ...”
December 20, 2013
“Hey Dan! I''m glad that the question makes sense now. Kaplan''s Premier Guide has a chapter devoted to statistics, which includes perms & combs (and of course those questions show up on our CATs). Whether that''s "enough" to get you through to test day depends on how much work ...”
December 18, 2013
Stuart Kovinsky posted a reply to Im not able to undersatnd and visualise this scenario in the Problem Solving forum
“Hi! Picking numbers is a great way to approach this question. However, you got a bit lost partway through your solution. Let''s go back a few steps! First, let''s state our task: We need to solve for the % greater Karen runs with gimpy John than with healthy John. In other words, percent ...”
December 18, 2013
Stuart Kovinsky posted a reply to Verb Tense, Mood, & Voice - MGMT SC in the Sentence Correction forum
“Hi Ian! Great job identifying that this sentence calls for the subjunctive mood. I like that term "bossy verb" - I''m going to steal that and pretend I made it up! Here''s the bare syntax for using the subjunctive: [subject 1] [bossy/question verb] that [subject 2] [infinitive ...”
December 18, 2013
Stuart Kovinsky posted a reply to Median question in the Data Sufficiency forum
“Hi! Here''s a thread that discusses this problem in detail: [url]http://www.beatthegmat.com/median-question-t8140.html[/url] If you still have questions about it, ask away! Stuart”
December 18, 2013
“No - the question is written in such a way that those 2 people are fixed (even if they''re not named). For the purposes of our calculation, it doesn''t matter which 2 people don''t get along. Now I feel like you''re arguing just for the sake of arguing! :D”
December 17, 2013
“Here''s the key difference: there''s only one way to choose the 2 consultants who can''t be together. There are multiple ways to choose the 8 male members of the jury. Technically, when calculating the number of disqualified teams of consultants, we''re calculating: 2C2 * 5C2 = 1*10 = 10 ...”
December 17, 2013
Stuart Kovinsky posted a reply to 1000CR Test 4 Q14 in the Critical Reasoning forum
“Hi Aditya! The opponents argue that people should be free to decide whether to wear seatbelts based on the rule that "you can do what you want as long as you don''t harm OTHERS". (e) doesn''t weaken because the non-seatbelt wearers are only harming themselves - something the ...”
December 17, 2013
“In this part of the solution, you''re ONLY looking at the unacceptable teams. In other words, you''re counting how many teams are disqualified due to inclusion of the 2 arch-enemies. Since we only care about disqualifying teams including the 2 troublemakers, we automatically include both of them ...”
December 17, 2013
“Your final solution for that problem was 2*3*25. So, in that problem you multiplied by 2 (possible choices for PM) and 3 (possible choices for TL) - you didn''t ignore those parts of the puzzle at all.”
December 17, 2013
“Speaking specifically to your solution, the problem in each case is when you begin with: There are 10 males total, so there are 10C8 ways to select those 8 males. You need to factor all those possibilities into your solution as well. (10C8 = 10*9/2*1 = 45) In the second case, you have to ...”
December 17, 2013
“Hi! Here''s another thread on this question in which I looked at a both algebra and strategic guessing. [url]http://www.beatthegmat.com/i-suck-at-probability-need-desperate-help-t8927.html[/url] Stuart”
December 17, 2013
Stuart Kovinsky posted a reply to Functions f(x) in the Problem Solving forum
“Hi! The most effective (and sometimes only) way to approach Two-part Analysis questions in IR is backsolving: using the choices to generate the matching pair of answers. There''s an infinite number of solutions for the problem, which is why you can''t "front-solve" them. Instead of ...”
December 17, 2013
Stuart Kovinsky posted a reply to interesting CR in the Critical Reasoning forum
“Hi again! One thing that it''s very important to remember: we accept the evidence as true. It''s not our job to discredit the evidence itself, but rather how the author uses that evidence. The vulnerable part of every argument is always the author''s assumptions: the missing but necessary ...”
December 17, 2013
Stuart Kovinsky posted a reply to interesting CR in the Critical Reasoning forum
“The GMAT is written according to patterns; understanding those patterns and how the test works gives you a huge advantage over your competitors. Here, we''re asked to weaken the argument. So, we need to break it down and determine what the author is assuming, then look for an answer that attacks ...”
December 16, 2013
Stuart Kovinsky posted a reply to weighted averages in the Problem Solving forum
“A mixture of 20 grams of lean ground beef is mixed with 50 grams of fatty ground beef to create a ground beef mix with 8% fat. How many grams of fat does the lean ground beef have? The ratio of fat content for L:F is 2:5. So, as GGNY (does he have a real name - does anyone know it?) aptly ...”
December 16, 2013
Stuart Kovinsky posted a reply to Equilateral triangle inscribed in a circle in the Problem Solving forum
“Hi! There''s an excellent chance that on test day you''ll see a question that involves the circle sector formula - that''s exactly what we have here. Here''s the formula: length of arc/circumference = angle of arc/360 = area of sector/area of circle In other words, every aspect of the ...”
December 16, 2013
Stuart Kovinsky posted a reply to x divisible by 6? in the Data Sufficiency forum
“Hi there! Not much to dissect for the q stem: we can rephrase it as "is x a multiple of 6?" No info provided, so we know nothing! (1) (x+3) is a multiple of 3, which means that x is also a multiple of 3. if x=3, then x is NOT divisible by 6. if x=6, then x IS divisible by 6. ...”
December 16, 2013
Stuart Kovinsky posted a reply to line k in xy-plane in the Data Sufficiency forum
“Hi there! We know that line K passes through the origin, so it must pass through exactly 2 of the 4 quadrants (ab isn''t 0, so we know that line K isn''t just one of the axes). Q: is b positive? We need info about which quadrant point a,b is in. (1) the slope is negative. If the slope ...”
December 16, 2013
Stuart Kovinsky posted a reply to Square inscribed within a circle in the Data Sufficiency forum
“Hi! 1. yes, they do (the diagonals of non-square rectangles also bisect each other, but not at right angles). 2. yes! The 4 angles have to add to 360 and they''re equal, so each one is 90 degrees. And, in case anyone is wondering, each statement is sufficient since each one proves that ...”
December 16, 2013
Stuart Kovinsky posted a reply to Pigs or cows in the Data Sufficiency forum
“Quick note: as written, (1) is both sufficient and impossible. Brent corrected the statement in his explanation. (I say (1) is impossible because it would require the farm to have (2/3)(40) = 26 2/3 cows, which is both messy and illegal in some states.)”
December 16, 2013
Stuart Kovinsky posted a reply to discounted airline tickets in the Critical Reasoning forum
“Hi! What''s the source of this question? The author definitely isn''t assuming (b), so if that''s the accredited answer, it''s just a bad question. The author is, on the other hand, assuming (a) - so your first instinct is correct! Breaking down the stimulus: Old plan had cheap prices ...”
December 14, 2013
Stuart Kovinsky posted a reply to weighted averages in the Problem Solving forum
“Sure - based on the original question, both the lean and the fatty could be 8% (or many many other combinations) and generate a different # of grams of fat. You have 2 unknowns but only 1 equation, so there''s an infinite number of solutions. Stuart”
December 14, 2013
Stuart Kovinsky posted a reply to weighted averages in the Problem Solving forum
“Hi! Did you omit something from the Q? Unless we know the % fat in the "fatty" ground beef, we can''t answer the Q.”
December 13, 2013
Stuart Kovinsky posted a reply to proportion of women in the Critical Reasoning forum
“Hi! When asked to find the answer that would most help you evaluate the argument, look for the gap - in other words, the author''s assumption. The correct answer will be directly relevant to determining whether the assumption is valid. Here, we have a classic scope shift. The author is ...”
December 11, 2013
Stuart Kovinsky posted a reply to Source : GMAT PREP :New Q for old stimuli. in the Critical Reasoning forum
“Certain patterns recur regularly in CR - possibly the most common argument form is causation. We can paraphrase this entire argument as "the increase in price is responsible for the decrease in sales". The most common ways to strengthen a causal argument are: 1) eliminate ...”
December 11, 2013
Stuart Kovinsky posted a reply to Pls explain with a diagram-what is diametrically Opposite in the Problem Solving forum
“Hi! This seems like a somewhat insanely complicated question! However, our old friend backsolving will save us from having to do crazy math. First, "diametrically opposed" means, literally, "at opposite ends of a diameter of the circle". In other words, they''re directly ...”
December 11, 2013
“Hi Dan! You''re right, this question is as much about logic as it is about math. We can paraphrase the question (a great thing to do with long word problems) as: Now let''s apply some logic: x will always be either somewhere ahead of y or somewhere behind y. Is there a reason why he ...”
December 10, 2013
Stuart Kovinsky posted a reply to Is 2^x greater than 100? in the Data Sufficiency forum
“Hi! We have a yes/no question, so if we can get a definite YES or a definite NO, we have sufficiency. If we get a maybe/sometimes/depends, we have insufficiency. Looking at the stem, we think "we need to know about x". (1) gives us an equation to solve for x. If we can solve for ...”
December 10, 2013
Stuart Kovinsky posted a reply to Female employes in X in the Data Sufficiency forum
“Hi! Without any doubt, the most powerful concept for data sufficiency is "number of equations vs number of unknowns". You can use that rule (and its exceptions) to solve many DS questions without doing much, if any, math. Let''s apply it to this particular question. Step 1 of the ...”
December 10, 2013
Stuart Kovinsky posted a reply to How to Buy Kaplan Premier GMAT Test Series in the Ask a Kaplan representative forum
“Hi! We devote a lot of resources to "norming" our CATS to be as close to the real GMAT as possible (and we''re constantly updating them as we get new information). While no prep company has access to GMAC''s actual algorithms, I''m confident that Kaplan gets as close as possible. It ...”
December 10, 2013
Stuart Kovinsky posted a reply to Usage of whom in the Sentence Correction forum
“Hi! A great way to determine whether to use "whom" or "who" is to turn the sentence into a question and answer it with "he" or "him". For example, for (B) we''d ask "by whom were the mountains named?" We''d answer: "they were named by ...”
July 16, 2013
Stuart Kovinsky posted a reply to Weighted Average Problem in the Problem Solving forum
“Hi there! My first post on the site for a while, but I can''t resist a good PM! As Matt notes, your solution is 100% correct - a really important thing to remember about high level GMAT questions is there''s almost always an "angle" to solving them - and if you find the right one, ...”
July 16, 2013
Stacey Koprince posted a reply to 2010 - Best GMAT practice tests in the GMAT Strategy forum
“Hi, guys, someone just pointed something out to me and I came here to correct a small piece of misinformation. It''s actually not the case that MGMAT CATs automatically give you something harder for the very next question when you get something right or easier when you get something wrong. We ...”
December 5, 2012
Stuart Kovinsky posted a reply to Coordinate Geometry in the Data Sufficiency forum
“We didn''t get lucky - the question was designed to reward people who saw the quick solution. Most GMAT math questions are designed with 4 levels of reward: 1) negative reward, for people who spend time on it and get it wrong; 2) 0 reward, for people who recognize that they don''t know how to ...”
August 21, 2012
Stuart Kovinsky posted a reply to applications in the Data Sufficiency forum
“You''re 100% correct about the interpretation, but not about the confusion. We don''t know how deposits and acceptances relate to enrolments, which is why the statements, even combined, are insufficient.”
August 20, 2012
Stuart Kovinsky posted a reply to Coordinate Geometry in the Data Sufficiency forum
“Hi! This question should take about 15 seconds if you actually draw out the x-y plane. There are no bonus points on the GMAT for super-complicated math, so avoid it whenever possible! If you plot the 2 points, you can see that, since they have the same y-coordinate (-3), one point that''s ...”
August 20, 2012
Stuart Kovinsky posted a reply to applications in the Data Sufficiency forum
“I don''t think that the problem with this question is that the language is confusing; rather, neither statement is relevant to the question, so we can very quickly say that the answer is (E). The question asks what % of students who apply actually enrol. Neither (1) nor (2) mentions enrolment, ...”
August 20, 2012
Stuart Kovinsky posted a reply to OG 13 #132 in the Data Sufficiency forum
“Hi! Normally for this type of question we can rely on our old friend, "number of equations vs number of unknowns". However, there are some cases, such as this one, in which you have more info that you originally thought and you don''t actually need as many equations as you may think. ...”
August 19, 2012
Stuart Kovinsky posted a reply to how do i solve this? in the Problem Solving forum
“Great job! Here''s a bit of clarification on solving this type of problem. There are simple rules for multiplying exponents (x^a * x^b = x^(a+b)) and raising exponents to other exponents ((x^a)^b=x^(a*b)), but there''s no simple way to add or subtract exponents. In fact, the only time you ...”
August 19, 2012
Stuart Kovinsky posted a reply to manufacturing in the Problem Solving forum
“Hi! Like many GMAT questions, this one looks much more difficult than it actually is. First, we can simplify by recognizing that the numbers on the right side are wholly irrelevant. The question would have an identical solution if the original equation were: C = rst Since that equation ...”
August 19, 2012
Stuart Kovinsky posted a reply to revolutions in the Problem Solving forum
“Hi! You can solve this doing a lot of math, but any time you have variables in the choices, you can also pick numbers to solve - and picking numbers is often much easier than algebra. Let''s try it a couple of different ways! Before we jump in, let''s make sure we identify exactly what the ...”
August 19, 2012
Stuart Kovinsky posted a reply to cabbage in the Problem Solving forum
“Hi! As always, let''s start by identifying the exact question: what''s the gross profit? Well, gross profit = total revenue - total cost. We''re given the total cost of $600, so we need to find the total revenue. We''re told that 2/3 of the heads were sold for 25% above cost/head. There ...” August 18, 2012 Stuart Kovinsky posted a reply to OG 12 DS #89 in the Data Sufficiency forum “Hi! While you certainly can solve by manipulating equations, you can also solve with common sense and logic - very powerful tools on the GMAT that people often overlook. We should be able to dismiss each statement by itself fairly quickly, since they each give us one relationship that''s not ...” August 18, 2012 Stuart Kovinsky posted a reply to Stats.. relationship among different pieces in the Problem Solving forum “1,3,5,5 is the same as 1,1,3,5 Similarly, 1,5,5,5 is the same as 1,1,1,5 The missing set is 1,1,5,5 On a side note, you will NEVER need to calculate SD on the GMAT (and, accordingly, you don''t need to know the SD formula) - you just might need to know what SD measures (how spread out are ...” August 18, 2012 Stuart Kovinsky posted a reply to median question.. in the Data Sufficiency forum “Hi! We''re told that 25% of projects have 4+ employees and 35% have 2- employees. Since the only number that doesn''t fall into "4 or more" and "2 or fewer" is 3, all of the remaining projects must have exactly 3 employees.” August 18, 2012 Stuart Kovinsky posted a reply to x/y<0? in the Data Sufficiency forum “Hi! While this question illustrates some important concepts, it is 100% NOT a real GMAT question. What''s the source? As TheCEO notes, statement (1) proves that the answer is "no" and statement (2) proves that the answer is "yes". On the GMAT, the two statements will ...” August 18, 2012 Stuart Kovinsky posted a reply to Martin's theory in the Reading Comprehension forum “Hi! Let''s look right at the beginning of the passage: Since the new research indicates that humans arrived "much earlier than 11,000 years ago", it directly attacks Martin''s theory that the arrival (i.e. not just the presence) of humans was responsible for the mass extinctions ...” August 18, 2012 August 6, 2012 August 6, 2012 shovan85 posted a reply to concept of "OCTAVE " in RC in the Reading Comprehension forum “I don''t know if it is really helpful!! Unless you can recognize the Tone/Opinion of the passage this tool is least helpful. Anyways that''s just an opinion :) Below is the link for OCTAVE - (Scroll the video to 1:11:08/2:36:48) http://www.youtube.com/watch?v=9NApwEPHyOA This is being taught ...” August 6, 2012 shovan85 posted a reply to meteor stream in the Reading Comprehension forum “IMO C” August 2, 2012 shovan85 posted a reply to meteor stream in the Reading Comprehension forum “Choice A - the computer model confirmed the astronomers’ hypothesis that meteor streams broaden with time, and although the model yielded an unexpected result, the passage does not contrast the predictions yielded by competing theories. Choice B - Best answer. The author describes the new ...” August 2, 2012 shovan85 posted a reply to About twice every century, one of the massive stars in the Reading Comprehension forum “I do not agree with this answer of yours!! Rest all I got the same as those of yours. Can someone please help with below kind of problems?” July 31, 2012 July 31, 2012 shovan85 posted a reply to School Survey in the Critical Reasoning forum “Yes! And also, most students attend services for social reasons, and not religious reasons, that would seriously weaken the author''s argument.” July 27, 2012 shovan85 posted a reply to In archaeology, as in the physical sciences in the Reading Comprehension forum “Easily discard B,C, and E. IMO the main idea is in Green - it says about UNDERMINING the existing theories. See the red highlight part in passage and Zeresenay Alemseged says about a finding in the history with some evidence. Honestly, I was confused between A and D, but marking each word of D ...” July 27, 2012 shovan85 posted a reply to Scientists !! in the Sentence Correction forum “Subjunctive mood - Discard B and C D and E - the scientists believe , however, the structure of these two says it is widely believed. IMO A” July 26, 2012 shovan85 posted a reply to Help Required !! in the I just Beat The GMAT! forum “Have a look at this awesome debrief! http://www.beatthegmat.com/770-q-51-v-46-ir-8-how-an-iit-guy-cracked-the-gmat-t115958.html Obviously you have no issues in Quant. Suggested books are there in the post. This member has mentioned all the Verbal books you need! Have a fresh start. Take a ...” July 26, 2012 shovan85 posted a reply to School Survey in the Critical Reasoning forum “I understand this problem can be solved by POE. However, when you are dealing with Percentage and when you see strong words as MUST, you have to be cautious. PERCENTAGE - You do not know how many students are in the religious service. For instance there were 1000 students in Total and Religious ...” July 26, 2012 shovan85 posted a reply to School Survey in the Critical Reasoning forum “Left with A and D. As far as D is concerned, NOT ALL STUDENTS - that means with data from LESS students who attend the services, gives the survey a claim saying it''s decreasing the incidences of cheating! So, if the survey includes all students, that will STRENGTHEN the argument. D strengthens the ...” July 26, 2012 shovan85 posted a reply to School Survey in the Critical Reasoning forum “If 15 years ago a stringent role has been applied, then how come cheating has decreased over last 10 years (Can have a look at the passage BOLD part). IMO C cannot be the answer.” July 26, 2012 shovan85 posted a reply to clueless & confused in the Sentence Correction forum “I will be honest! I don''t remember any rule saying In parallelism, you cannot compare Singular to Plural Or Vice-verse. As both are available, I rule out Singular here so A, B, and D. Among C and E, E has two issues: 1. "Condominium apartment owners" not parallel to "Owners of ...” July 25, 2012 shovan85 posted a reply to problem of/in in the Sentence Correction forum “We cannot categorize this question as per "OF / IN". However, while managing something if you say "Problems of Managing..." then it means that the problems are outcome (sort of) of the managing of X. Whereas, when in you face problems during the management of X, then it can be ...” July 25, 2012 shovan85 posted a reply to hurricane in the Sentence Correction forum “Please post all the options - Helps others as well! The sentence says that the study is not practical. However, D says the tornado not making the study practical.” July 25, 2012 shovan85 posted a reply to same as/similar to/like usage ??????????? in the Sentence Correction forum “It''s a question of Parallelism and Like/As. Going with the gerund "Trying to...", I would prefer "Tinkering with...". Going with parallelism IMO C ” July 25, 2012 shovan85 posted a reply to Sviatovin (OG13 49) in the Critical Reasoning forum “(A) No connection between the text timeline and this option - we are not talking about Prince! (B) Accuracy of the report about Prince - nothing to do with the text. (C) the diagram accurately represents the composition of Sviatov''s family at the time Sviatovin was written (Left out) (D) We ...” July 25, 2012 shovan85 posted a reply to Kiowi matriach, Aho in the Sentence Correction forum “For eliminating A, you can see the pronoun "They" is ambiguous, as it may refer to Home or it may refer to Festivals. As, home is singular we know that "they" points to "festivals" - but grammatically wrong. Consider, if those were homes instead of home.” July 24, 2012 shovan85 posted a reply to As a part of their therapy in the Sentence Correction forum “practice falling during the 1950s as part of their therapy .... Feels as if they were helped to practice falling at that period of time only. Practice falling during 1950s only not beyond that. Clearly, distorts the intended meaning.” July 24, 2012 shovan85 posted a reply to Madagaskar in the Sentence Correction forum “What should be cultivated - Madagascar periwinkle or the derivative? Only option E says what is cultivated.” July 23, 2012 shovan85 posted a reply to Sedan Holiday in the Problem Solving forum “Total Ways = Driver seat (2 ways) * 4 * 3 * 2 = 48 ways Say the two sisters sit together S1 and S2 S1,S2 sequence possible ways = Driver seat (2 ways) * Next Front Seat (2 ways other parent and son) * Back remaining 1seat (2 ways son and other parent) * rest 2 back seats (1 way) = 8 ways Now, ...” July 23, 2012 Stuart Kovinsky posted a reply to Two glasses contain milk and water. In the first glass the r in the Problem Solving forum “Just a brief follow up - the problem is that we don''t know how much liquid was in each glass to start - without that info (or at least the relative volumes of the glasses), there''s no way to answer the question. The fact that there are only 4 answer choices should also raise red flags, since a ...” July 23, 2012 Stuart Kovinsky posted a reply to inequalities problem... again in the Problem Solving forum “As usual, Eagleeye provides a great explanation - using the number line is a great way to solve absolute value problems. Another way to solve, especially when you have absolute value expressions on both sides of the equal sign, is to square both sides. Doing so generally leaves you with a ...” July 22, 2012 Stuart Kovinsky posted a reply to Adam Family in the Problem Solving forum “Hi! You can solve this almost instantaneously if you understand what the question is asking. Since each brother is double the weight of the previous brother, the correct answer has to be divisible by 2 many times. The only answer that has lots of factors is 2 is 64... choose E! The ...” July 22, 2012 Stuart Kovinsky posted a reply to Problem Solving - Factorization Question?? in the Problem Solving forum “Hi! This is an old question (and actually quite poorly constructed), but it illustrates a common feature in some GMAT questions, so it''s worth reviewing. First, let''s break down the question: Whenever you see this type of question, always rewrite it as: n x 25 x 62 x 73/(5^2 * 3^3) = ...” July 22, 2012 Stuart Kovinsky posted a reply to Exponents problem in the Problem Solving forum “Let''s look at another approach we can take to the one posted by eagleeye. First, a note of caution: when dealing with inequalities, be very wary of multiplying or dividing both sides by variables. Remember, if those variables turn out to be negative you have to reverse the inequality. ...” July 22, 2012 Stuart Kovinsky posted a reply to Geometry problems: in the Problem Solving forum “Using the vertical angle rule (opposite angles of intersecting lines are equal), we know that: a=d and b=e So, since a and b are complementary, d and e must also be complementary. Further, since a=d, b and d are complementary; similarly, since b=e, a and e are complementary. We know ...” July 22, 2012 Stuart Kovinsky posted a reply to Ratios problem in the Problem Solving forum “Hi! A bit of theory before getting into the calculations. First, when converting between linear, second order and third order equations (i.e. lengths, areas and volumes), you simply apply the proper exponent to find the new ratio. For example, if comparing the areas of two squares with ...” July 22, 2012 shovan85 posted a reply to CR weaken question in the Critical Reasoning forum “A - Do not know about the Participation of Citizen to achieve the target! B - Left out - the answer. C - The program is already profitable. Difficulty, cost-effectiveness cannot come to picture! D - Not concerned about pollution. Recycling is a PREFERABLE alternative which is demonstrated! E - ...” July 21, 2012 shovan85 posted a reply to diameter of the circle? (GMAT Prep 2) in the Problem Solving forum “Equilateral Triangle, AB = BC = CA, So, for the circle Arc AB = Arc BC = Arc CA Arc ABC = Arc AB + Arc BC = 24. Thus, Arc Arc AB = 12 = Arc BC = Arc CA So, perimeter of the circle = Arc AB + Arc BC + Arc CA = 3* 12 = 36 (as all Arc are same) 2*pie* radius = 36 => radius = 36/(2*pie) = ...” July 21, 2012 Stuart Kovinsky posted a reply to "Rounded to the nearest" - What does that term mea in the Problem Solving forum “Hi! "Rounding" means evening things off to the nearest unit mentioned. For example, "rounded to the nearest mile" means that you eliminate all decimal points. "Rounded to the nearest hour means that you ignore minutes and seconds. To properly round off, you can ...” June 17, 2012 Stuart Kovinsky posted a reply to Usage of Has-Experts please help in the Sentence Correction forum “Hello! "None of them have" and "none of them has" are both in common usage. While "none of them has" is technically "more correct", arguments can (and have!) been made for using "have" instead. I can''t recall a GMAT question that required you ...” June 12, 2012 Stuart Kovinsky posted a reply to DS: Finding percents from averages in the Data Sufficiency forum “Hi! Dimochka presents a great mathematical explanation, but let''s focus on efficiency, remembering one key rule: To get the point on a DS question, you don''t need to actually answer the question - you just need to determine whether it''s possible to do so. Keeping this rule in mind will ...” June 8, 2012 Stuart Kovinsky posted a reply to NEW ENTRY PROBLEMS in the Problem Solving forum “Hi! If it''s actually a numeric entry question, then you have to enter the answer on the computer - it''s not multiple choice. Again, these questions do NOT appear on the GMAT.” June 8, 2012 Stuart Kovinsky posted a reply to Integers x and y in the Data Sufficiency forum “Hi! If x+2 and x+4 are between x and y, won''t x+1 and x+3 be between them as well? You''re misinterpreting statement (2) as: when in fact statement (2) simply tells us that there ARE 24 integers between x and y... period. The only way this statement can be be true is if y = x + 25 ...” June 8, 2012 Stuart Kovinsky posted a reply to Primes in the Data Sufficiency forum “Hi! Like a lot of data sufficiency questions, investing a bit of time in the question stem to understand what the question is really about makes working with the statements much simpler. Let''s break down the stem: What kind of positive numbers CANNOT be expressed as the product of two ...” June 8, 2012 Stuart Kovinsky posted a reply to NEW ENTRY PROBLEMS in the Problem Solving forum “Hi! Is this a GRE question? There are no entry questions on the GMAT. The first thing to note is that, on the GRE, you actually have access to a calculator. While you don''t need to use it (in fact it''s often quicker to solve multiple choice questions without a calculator), on the numeric ...” June 8, 2012 Stuart Kovinsky posted a reply to Problem solving - Ratio / Proportion in the Problem Solving forum “Hi! As the other experts noted, this is a really tough math problem - which is why, almost certainly, the best way to approach it is strategically. If you had provided answer choices (please always provide the choices!), we could have backsolved. When you have a very complicated word problem ...” June 8, 2012 Stuart Kovinsky posted a reply to OG 10th edition CR-q174 in the Critical Reasoning forum “Hi, the question stem tells us to draw a conclusion "from the information given above". Two of those pieces of info are: So, we do definitely know that the average age will increase over that time period.” June 6, 2012 Stuart Kovinsky posted a reply to really tough CR.. in the Critical Reasoning forum “Hi! For assumption questions, start by deconstructing the argument: identify the author''s conclusion and summarize the evidence. Conclusion: the ONLY solution is to increase the number of government officials. Evidence: old folk are underrepresented in the government, which sets policy ...” June 5, 2012 Stuart Kovinsky posted a reply to BOLD in the Critical Reasoning forum “Hi! Bolded statement questions can be tricky, mostly because the answers often sound extremely similar. To avoid getting confused, rely on the most powerful tool for both RC and CR: making a prediction. The best way to make a prediction on bolded statement questions is to roadmap the ...” June 5, 2012 Stuart Kovinsky posted a reply to I didn't even understand the question! in the Problem Solving forum “Hi! A terminating decimal is one that ends, i.e. doesn''t infinitely repeat. For example, 1.4, 8, 32.888991 and 27.6 are all terminating decimals. Some fractions can be turned into terminating decimals, some can''t. For example, 1/3 is .33333 (going on forever). 1/5 is .2, which is ...” June 5, 2012 Stuart Kovinsky posted a reply to number of solutions in the Problem Solving forum “Both! 0 is an uncharged (i.e. neither positive nor negative) even integer. As an aside, all integers are rational (but not the other way around).” June 5, 2012 Stuart Kovinsky posted a reply to As part of a game, four people each must secretly in the Problem Solving forum “Here''s another way you can solve: Prob = # desired outcomes/total number of possibilities there are 4*4*4*4 = 256 total possibilities Now on to desired outcomes! The first person can pick any number, so she has 4 possibilities. We want the second to be the same as the first, so she has ...” June 5, 2012 Stuart Kovinsky posted a reply to From new GMATprep Qn - Experts help please in the Problem Solving forum “Hi! There''s a problem with the question - it doesn''t make sense as written (at least if the answer is supposed to be D). You have Betty and William earning more than 50000, but then we never hear about William again. Then the question asks whether Wilma''s annual salary is greater than ...” May 27, 2012 Stuart Kovinsky posted a reply to the long advertisement in the Critical Reasoning forum “Correct!” May 26, 2012 Stuart Kovinsky posted a reply to Inequalities DS in the Data Sufficiency forum “Sure! We want to know if the absolute value of a is greater than the absolute value of b. In other words, is the magnitude of a greater than the magnitude of b? (I.e. is a further from 0 on the number line than is b?) As always, let''s start with the simpler of the two statements (that way if ...” May 26, 2012 Stuart Kovinsky posted a reply to Inequalities DS in the Data Sufficiency forum “Hi! We want to know if the sum of x and y is positive. So, we either need the individual values of x and y or information about the expression "x+y". (1) x - y > 0 We know nothing about x and y individually, so (1) is insufficient. If the concepts don''t jump out at you, ...” May 26, 2012 Stuart Kovinsky posted a reply to Probability problem in the Problem Solving forum “That''s the exact rule! If you just care about which objects to select, then you use the combinations formula. If you care not only about which objects to select, but also the order of selection (or arrangement), then you use the permutations formula. Here are two examples to illustrate the ...” May 26, 2012 Stuart Kovinsky posted a reply to the long advertisement in the Critical Reasoning forum “Hi! Just a reminder, please post the source of your questions (always a good habit). Whenever you have an assumption family question (assumption/strengthen/weaken/flaw), start by deconstructing the argument: find the conclusion, summarize the evidence and identify the assumption. Here, we ...” May 26, 2012 Stuart Kovinsky posted a reply to Probability problem in the Problem Solving forum “Just to elaborate a bit more, here''s the probability formula: probability = (# of desired outcomes)/(total # of possibilities) and, as Anurag noted, 36 was the total number of possible choices. Whenever you''re doing a probability problem, starting out by writing that equation on your ...” May 26, 2012 Stuart Kovinsky posted a reply to Coordinate plane in the Problem Solving forum “Hi! Let''s start with what''s probably the quickest approach: actually graphing the line. The notepad that you get on the GMAT is graph-lined, so it''s pretty easy to accurately draw out coordinate geometry questions. Accordingly, one option for solving this problem is to plot the two points, ...” May 26, 2012 Stuart Kovinsky posted a reply to Quadrilateral in the Data Sufficiency forum “Hi! It''s been a long time since I read this thread, but happy to reiterate a couple of key points. First, and I can''t stress this enough: a square IS by definition a rectangle, since it has all the properties of a rectangle. The opposite is not true (i.e. a rectangle is not by definition a ...” May 26, 2012 Stuart Kovinsky posted a reply to Manhattan - weaken in the Critical Reasoning forum “Hello! We''re asked to find the answer that would be cited by a SUPPORTER of the argument; in other words, we want to find the answer that, if true, would most STRENGTHEN the conclusion. First, of course, we need to identify the conclusion. There are a number of tools we can use to do so: ...” May 24, 2012 Stuart Kovinsky posted a reply to Strengthen in the Critical Reasoning forum “Hi! For strengthening questions, start by deconstructing the argument: find the conclusion, summarize the evidence and identify the author''s assumption. Next, make your prediction: the correct answer will support the assumption. Let''s break down this argument: Conclusion - TV ...” May 23, 2012 Stuart Kovinsky posted a reply to Assumption question quiet confusing... in the Critical Reasoning forum “Hi! What''s the source of this question? It sounds a LOT more like an LSAT question than a GMAT one. If it''s from an LSAT source, then I''d advise that you completely ignore it, since the difference between sufficiency and necessity is rarely tested on the GMAT. **FEEL FREE TO STOP READING ...” May 23, 2012 Stuart Kovinsky posted a reply to Explain the Discrepancy CR Question - MGMAT CAT in the Critical Reasoning forum “Hi! (C) is outside the scope because of two key factors: 1) the stimulus tells us that the ATMs are "on the driver''s side of a lane accessible only to automobiles" and "Clearly, blind people do not drive automobiles"; and 2) (C) says that "all ATMs accessible to the ...” May 23, 2012 Stuart Kovinsky posted a reply to Something Wrong with the question??? in the Data Sufficiency forum “Hi! Remember - when inequalities and variables are involved, you have to be very careful with your manipulations! You cannot simply cross-multiply by a-b, since it''s possible that a-b is negative. If a-b IS negative, then when you cross multiply you get: Is 1/(a-b)<(b-a)? Is 1 > ...” May 23, 2012 Stuart Kovinsky posted a reply to stocks in the Problem Solving forum “Hi! At first glance this may look like a permutations question, but it''s actually an exponent question with a tiny bit of permutations thrown in. Since there''s no restriction on how many times we use each letter in each code, the number of possible 5 letter codes is simply 26^5 and the ...” May 23, 2012 Stuart Kovinsky posted a reply to households in the Problem Solving forum “Hi! I played with the numbers a bit to maximize the duplicates, keeping in mind that I wanted to use as many of the DVDs, cell phones and MP3 players as possible twice. I started with the MP3s, since that was the smallest group. Then I noted that there were 5 more Cell phones than DVDs, so I ...” May 22, 2012 Stuart Kovinsky posted a reply to three and four digit numbers in the Problem Solving forum “Hi! Is there a reason why we couldn''t have x=170 and y=850? In order for x+y to be a 4 digit number, at least one of the two must be greater than 500 (and the hundreds digits must sum to at least 9), but both don''t need to be greater than 500. Fortunately, that issue doesn''t cause any ...” May 22, 2012 Stuart Kovinsky posted a reply to Counting Numbers -1 in the Problem Solving forum “Hi! Because you''re multiplying by a smaller number, you''ve actually removed those duplicates. Here''s another way you could write the product: (number of digits that could go in the first spot) * (number of digits that could go in the second spot that you haven''t used yet) * (number of ...” May 22, 2012 Stuart Kovinsky posted a reply to advanced gmat guide- inequality in the Data Sufficiency forum “Hi! The two statements aren''t identical, since for (2) a could be the negative root of a^2 and for (1) a is definitely non-negative. For example, for statement (1) we could pick a=4 and b=2 (since 4 = 2^2). For statement (2) we could pick those same numbers (since 4^2 = 2^4), but we could ...” May 21, 2012 Stuart Kovinsky posted a reply to Consulting in the Data Sufficiency forum “Hi! From the stem, we know that the fee is$x/hour for the first 100 hours and $y/hour for extra hours. We also know that Acme was charged a total of$14000. So, we can create the following formula: 100*$x + (n-100)*$y = $14000 (n = total number of hours charged) and the question is ...” May 21, 2012 Stuart Kovinsky posted a reply to Probability | Playing Cards in the Problem Solving forum “Hi! We want the probability of getting at least one matching pair. So, the only thing we don''t want to happen is 0 matching pairs. Accordingly, this is a great question on which to apply the "one minus" approach. Remember this key formula for complex probability problems: ...” May 21, 2012 Stuart Kovinsky posted a reply to households in the Problem Solving forum “Hello! First, a key strategy on min/max questions: whenever a question asks you to minimize one thing, maximize others; whenever a question asks you to maximize one thing, minimize others. Next, let''s break this question down into two parts. First, the max number of households that has all ...” May 21, 2012 Stuart Kovinsky posted a reply to Sum of numbers in the Problem Solving forum “Hello! On this type of question you always want to look for a pattern. In this case, let''s separate the units and tens digits. Overall, we have 10 sets of numbers here: 0-9, 10-19, 20-29, ..., 90-99. In each set of 10, we have 1 of each units digit, so that''s 10 of each. For each set ...” May 21, 2012 Stuart Kovinsky posted a reply to prime in the Problem Solving forum “Hi! The wording of this question is a bit too ambiguous for the GMAT. Even though we can reason out what the question is supposed to say, you''ll never be put in that position on test day. What''s the source? Better wording would have been: Like many number property questions, we can ...” May 21, 2012 Stuart Kovinsky posted a reply to Coin flip questions made easy in the GMAT Math forum “Hi! The formula is more complicated for die rolls because there are more than 2 possible outcomes, so "what you want" doesn''t equal "what you don''t want". If you''re looking for one specific result, there''s a 1/6 chance of what you want and a 5/6 chance of what you ...” May 20, 2012 Stuart Kovinsky posted a reply to Problem Solving in the Problem Solving forum “Hi! We see a fraction question with unknown values. Perfect time to pick numbers! First, let''s identify the exact question: what fraction of UNSOLD cars were HYBRIDS. In other words, we want to solve for: (# of unsold hybrids)/(total # of unsold cars) To make the math work out, ...” May 19, 2012 Stuart Kovinsky posted a reply to 3 categories of workers in the Problem Solving forum “Hi again! I strongly disagree - you will never have to make assumptions of this nature on the actual GMAT and doing so in practice will lead to habits on test day that could lead to fatal errors. For example, one of the most common DS mistakes is to assume facts that aren''t actually in ...” May 19, 2012 Stuart Kovinsky posted a reply to 3 categories of workers in the Problem Solving forum “Where do you see that information in the question stem? Also, does a higher number in the ratio mean that a worker is more efficient or less efficient? For example, if you measure efficiency in tasks per hour, then higher is better; but if you measure efficiency in hours per task, then lower is ...” May 19, 2012 Stuart Kovinsky posted a reply to If 0<x<y, is y-x < 0.00005 in the Data Sufficiency forum “Sometimes brute force is the key to happiness on the GMAT. (1) doesn''t give us any information about the upper boundary of y, so there''s no way it''s sufficient by itself: eliminate A and D. (2) gives us an upper boundary on y AND we already know that x > 0, so it''s actually possible ...” May 19, 2012 Stuart Kovinsky posted a reply to 3 categories of workers in the Problem Solving forum “Hi! This is a very poorly worded question and makes little sense. What does "the efficiency of the 3 categories of workers" mean? How is it related to wage? Nowhere does it say that different workers get different hourly rates (e.g. that hourly wages are proportional to efficiency, ...” May 19, 2012 Stuart Kovinsky posted a reply to Maths Problem in the Problem Solving forum “Hi! Since p is a positive integer, p^3 is a perfect cube. Here''s an important rule about prime factoring of perfect squares, cubes, etc...: perfect squares contain prime factors in pairs; perfect cubes contain prime factors in triplets; and so on... For example: 36 is a perfect square; ...” May 19, 2012 Stuart Kovinsky posted a reply to Sets in the Data Sufficiency forum “Hi! I can''t speak for all the experts here, but when I see a question linked in an image instead of typed in, I usually skip over replying (unless the image contains a diagram, which is a good excuse for attaching one). The reason why I skip over these posts is because 90% of the time I''m ...” May 19, 2012 Stuart Kovinsky posted a reply to board of directors in the Problem Solving forum “A great opportunity to use logic instead of math! There are 5 different people with whom Michael can be matched. There are 2 spots available on Michael''s team. Therefore, any one of the other 5 people will appear on 2/5 = 40% of Michael''s teams. Pick C!” May 19, 2012 Stuart Kovinsky posted a reply to Can someone please explain? in the Problem Solving forum “Hi! We can set up a couple of simple equations to solve this relatively painlessly. Let''s call his one way walking time "W" and his one way cycling time "C". We want to know the time for walking both ways, so we''re solving for 2W. We know that: W+C = 2h40min ...” May 18, 2012 Stuart Kovinsky posted a reply to perpendicular in the Problem Solving forum “Hi! Although it may be somewhat time-consuming, your best bet is to rewrite the equation in the stem and in each choice into standard y=mx+b form - that way you''ll be able to quickly compare the slopes. Original: 3x + 4y = 8 4y = -3x - 8 y = -3/4(x) - 8 Slope = -3/4 Since ...” May 18, 2012 Stuart Kovinsky posted a reply to Probabilities in the Problem Solving forum “*TANGENT ALERT* No math here, if you''re looking for math, move along! There''s no need to put it directly before that (in fact, I challenge you to rewrite the sentence to put that where you want without causing a modification error in the remainder of the sentence) - the verb makes it clear ...” May 18, 2012 Stuart Kovinsky posted a reply to prime number in the Data Sufficiency forum “Hi! Very open question, but we see it''s about primes. Whenever you see a DS question about primes, always think about 2, the only even prime! Pretty straightforward question, so let''s dive right into the statements. (2) seems simpler, so let''s start there. The only way that (2) could ...” May 18, 2012 Stuart Kovinsky posted a reply to Probabilities in the Problem Solving forum “Hi! Because the sentence reads "that are", that must be referring to a plural subject; since "warehouse" is singular, it can''t be the referent of that.” May 18, 2012 Stuart Kovinsky posted a reply to Are x and y both positive? in the Data Sufficiency forum “Hi! (2) says that x/y > 1 If you plug in x = -3/2 and y = -2, you get: x/y = -(3/2)/-2 = -(3/2)*-(1/2) = 3/4 which is NOT greater than 1. Since your numbers don''t satisfy the statement, they''re impermissible and must be discarded. As Aneesh aptly notes, you have to be VERY careful ...” May 18, 2012 Stuart Kovinsky posted a reply to Overlapping sets - OG12 in the Problem Solving forum “Hi! Yes - if you want to solve with a Venn diagram, that''s exactly where you''d put the 60. Stuart” May 17, 2012 Stuart Kovinsky posted a reply to If a, b, and c in the Data Sufficiency forum “Hi! Picking numbers is a great way to solve this (and many other) DS questions. We quickly decide that (1) is insufficient, since it gives us no info about c. So, let''s eliminate A and D and jump to (2). (2) a-b>c We can see that b is to the right of a on the number line, so let''s ...” May 17, 2012 Stuart Kovinsky posted a reply to Are x and y both positive? in the Data Sufficiency forum “Eagleeye gives a good math explanation; let''s look at the question purely using number properties concepts. Q: are x and y BOTH positive. (1) 2x-2y=1 or x - y = 1/2 Let''s think about what this means: on the number line, x is 1/2 to the right of y. Does that tell us anything about ...” May 17, 2012 Stuart Kovinsky posted a reply to Overlapping sets - OG12 in the Problem Solving forum “Hi! You''ve put 60 in the Brand A "total" column, which includes "brand A/brand B" and "brand A/not brand B". People in the "brand A/brand B" column are NOT "brand A ONLY" - they''re using both. The 60 should go in the "brand a/not brand ...” May 17, 2012 Stuart Kovinsky posted a reply to Percentages in the Problem Solving forum “Hi! I''m not sure where you''re getting these questions, but they, for the most part, suck. Each one only has 4 choices, they often have awkward or ambiguous language and test concepts far beyond (and irrelevant to) the GMAT. If you''re actually studying for the GMAT, I''d avoid this source ...” May 17, 2012 Stuart Kovinsky posted a reply to Six digit numbers in the Problem Solving forum “Only 4 answer choices, so clearly this isn''t a real GMAT question - please always post your source we know if it''s relevant to the GMAT! This question is a far more complicated version of a question that may appear on the GMAT, so it''s worth discussing. Once you understand how one of these ...” May 17, 2012 Stuart Kovinsky posted a reply to Another good evaluate question... in the Critical Reasoning forum “But what does "coming second" mean? If the Bible got 999 votes and 1984 got 1 vote, then 1984 came second; if the Bible got 501 votes and 1984 got 499 votes, then 1984 came second. Do both scenarios make us think that 1984 actually affected a lot of people''s lives?” May 16, 2012 Stuart Kovinsky posted a reply to jury in the Problem Solving forum “Hi! I gave a detailed explanation to this question here: http://www.beatthegmat.com/i-suck-at-probability-need-desperate-help-t8927.html” May 15, 2012 Stuart Kovinsky posted a reply to Inequalities OG12 #38 in the Problem Solving forum “Hi! When you''re not sure what to do with the algebra, don''t waste your valuable test time trying to figure it out. Instead, dive right in and pick numbers. As you noted, each statement must be insufficient alone, since each one only provides 1/2 the picture. So, let''s jump right to ...” May 15, 2012 Stuart Kovinsky posted a reply to Another good evaluate question... in the Critical Reasoning forum “Hi! Relevant information questions are really scope questions - we want the answer that''s most inside the scope of the issue. These questions belong to the assumption family. A great approach is to break down the argument just as you would for any assumption/str/wkn question: find the ...” May 14, 2012 Stuart Kovinsky posted a reply to Couldn't get the problem in the Problem Solving forum “Hi! Wacky symbol questions appear from time to time on the GMAT; these questions almost always resolve to simple substitution. Of course, before you can substitute you have to understand the question. So, the key to solving these problems is to take the time you need to break down the question ...” May 14, 2012 Stuart Kovinsky posted a reply to Confusing Probability in the Problem Solving forum “Hi! Part of you''re analysis is 100% correct: for any given string of 7 coin flips, there''s a (1/2)^7 chance of it happening. For example, there''s a (1/2)^7 probability of getting: HHHHHHH; or HHHHHHT; or HHHHHTT; and so on... However, here''s the problem: to satisfy what the ...” May 14, 2012 Stuart Kovinsky posted a reply to weighted averages in the GMAT Math forum “Here''s a very useful rule to remember for data sufficiency: In order to find the actual value of a quantity, you need at least one actual quantity somewhere in the information. For example, if all you''re given is a ratio, there''s no way to determine the actual quantities involved; ...” May 12, 2012 Stuart Kovinsky posted a reply to Confusing Probability in the Problem Solving forum “Hi! We can definitely solve using the coin flip formula and adding up the probability of each scenario that we want. However, we can solve MUCH quicker using logic. We want all the cases with an even number of heads. So, we want: 0H 2H 4H 6h We DON''T want all the cases with an odd ...” May 11, 2012 Stuart Kovinsky posted a reply to MGMAT Geo series - Need expert help with my calculation in the Problem Solving forum “I have to admit that I''m not an expert on geometric series - I''d always attack this kind of question by picking numbers, which to me is much simpler. However, I think the problem is that you''re using "y" to mean different things in different places. You say that: In that ...” May 11, 2012 Stuart Kovinsky posted a reply to How to plug in for this? Official GMAC Hard in the Problem Solving forum “Hi! First, let''s make sure we understand the essence of the question - since we''re increasing by a set percent each year, what we really have here is a compound interest problem. The problem basically boils down to: Principle investment on Jan 1, 1992:$k interest rate per year: c% total ...”
May 11, 2012
Stuart Kovinsky posted a reply to Question pack 1 DS (hard section) in the Data Sufficiency forum
“Hi! Please check out: [url]http://www.beatthegmat.com/x-the-12th-power-of-an-integer-t110825.html[/url] for some expert explanations!”
May 11, 2012
Stuart Kovinsky posted a reply to remainder problem in the Problem Solving forum
“Hi! Picking numbers is a great approach to solving many number property questions. Here, our constraints are that n/9 must have a remainder of 8 and n must be even. What''s the smallest number that satisfies these constraints? n=8 (8/9 has a quotient of 0 and a remainder of 8). Now let''s ...”
May 11, 2012
Stuart Kovinsky posted a reply to abc in the Problem Solving forum
“Hi, those will indeed have different results, but since 6/2 doesn''t satisfy the condition that ab^2/c is even, we can ignore that possibility. Remember, we take the equation in the question stem as a given; accepting that the equation is true, we now check to see which statement MUST also be ...”
May 11, 2012
Stuart Kovinsky posted a reply to Single eqn solving?? in the Problem Solving forum
“Hi! We can solve this question super-duper quickly via backsolving. Since we want the minimum number of copper coins, let''s start with the smallest answer, (E). (E) 0 copper means $2.80 from brass - since 280 is not a multiple of 25, wrong! (D) 1 copper means$2.60 from brass - since 260 ...”
May 11, 2012
Stuart Kovinsky posted a reply to usage of will and would in the Sentence Correction forum
“It''s not wrong, it''s just overly wordy - and the GMAT doesn''t like overly wordy sentences.”
May 11, 2012
Stuart Kovinsky posted a reply to Remainder R in the Data Sufficiency forum
“Picking numbers is a very efficient way to solve number property DS questions. From the question stem, we know that (4+7n)/3 has a remainder of r; we want to know that value. What do we need? Information about n. 1) n+1 is a multiple of 3. If n=2 (we''re allowed to pick 2 since 2+1 is a ...”
May 9, 2012
Stuart Kovinsky posted a reply to Sets problem in the Data Sufficiency forum
“Let''s solve using the most powerful rule for data sufficiency: number of equations vs number of unknowns. First, picture (sorry, I''m not good at computer diagrams!) a Venn diagram with 3 circles. There are 7 different sections: Only R, only S, only T, RS overlap, RT overlap, ST overlap, RST ...”
May 9, 2012
Stuart Kovinsky posted a reply to usage of will and would in the Sentence Correction forum
“For the first one I''d say "there is hope that the economy will grow". You would only use "would grow" if you''re adding a "but" to the end. For example, "I had hoped that the economy would grow, but it shrunk." (Or "I hoped that the economy would grow, ...”
May 9, 2012
Stuart Kovinsky posted a reply to Confused - Any Ideas in the Problem Solving forum
“From the question stem, we know that n is an integer. Accordingly, we know that sqrt(3+x) is an integer. What numbers have roots that are integers? Perfect squares. Consequently, (3+x) must be a perfect square, i.e. 1, 4, 9, 16, 25, 36, ... Now we just need to plug in each answer to see ...”
May 8, 2012
Stuart Kovinsky posted a reply to usage of will and would in the Sentence Correction forum
“Hi, would is NOT the past tense of will. Would is used in conditionals, e.g. "I would go to Harvard if I were to get an 800 on my GMAT". Would can be used in different tenses. For example: I would have gone to Harvard if I had gotten an 800 on my GMAT. "Will" ...”
May 8, 2012
Stuart Kovinsky posted a reply to function h(n) number properties in the Problem Solving forum
“Here''s the takeaway: if h(100) is divisible by every prime from 1 to 50, then h(100)+1 CANNOT be a multiple of any of those numbers. What Bill was saying is that the greatest common factor of any TWO consecutive integers is 1. Since h(100) and h(100)+1 are consecutive integers, then any prime ...”
May 7, 2012
Stuart Kovinsky posted a reply to Airline Fleet - GMAT Prep in the Problem Solving forum
“You can think of it that way, but you have to count the actual number of years starting from the beginning of 1980. I guess technically you''d hit your target 8 years and 364 days after you start, but that''s still 9 years, not 8. (If you start on Jan 1st 1980, you have your 9th change on Dec 31st ...”
May 4, 2012
Stuart Kovinsky posted a reply to numbers 2 in the Problem Solving forum
“Hi, I''m happy to explain the concepts, but first it''s important to note that the wording of both questions is definitely NOT what you''d see on the GMAT. Also, there are only 4 answer choices and, of course, on the real GMAT there will be 5. Please always post the source of your questions so ...”
May 4, 2012
Stuart Kovinsky posted a reply to Airline Fleet - GMAT Prep in the Problem Solving forum
“Hi! You could solve this question very quickly by brute force - just make a chart and keep track of what happens each year. Remember, on the GMAT you get points for picking the right answer, not for HOW you arrive at that answer. Sometimes brute force is quicker than algebra. Year A planes ...”
May 3, 2012
Stuart Kovinsky posted a reply to OG 13 #229 How many of the integers... in the Problem Solving forum
“Here''s the #1 thing to remember when using the OG: it''s a great source of questions, but a horrible source of explanations. Especially for math, OG explanations are rarely the most efficient way to solve problems. Since the biggest answer given is 5, plug ''n play is a great alternative way ...”
May 3, 2012
Stuart Kovinsky posted a reply to if b < 1 and 2x - b = 0 in the Problem Solving forum
“Hi! Like many GMAT questions, we should start by simplifying the question itself. We know that b < 1 and that 2x-b=0. We can rewrite the equation as: 2x = b Putting the two statements together: 2x = b < 1 2x < 1 x < 1/2 Now we need to find the answer that MUST be true, ...”
May 3, 2012
Stuart Kovinsky posted a reply to Probability of cars in the Problem Solving forum
“Hi! Lots of good solutions already posted, so I''m just going to focus on your actual question. When we made the calculation to get 192, we were working on the basis that order DID matter. If you think about those possibilities, you''ll see that we''ve over counted. For example, if the ...”
May 3, 2012
Stuart Kovinsky posted a reply to Thought process on remainders in the Problem Solving forum
“Hi, for the GMAT, your goal is to be as efficient as possible. While you could certainly derive a fancy formula to solve this type of problem, brute force is almost certainly quicker. Since we want all the numbers that leave a remainder of 1 when divided into 16, what we really want is the ...”
May 3, 2012
Stuart Kovinsky posted a reply to Quadratic Equation in the Data Sufficiency forum
“Hi! There are two problems with your analysis, one of which may just have been a typo. First, the minor issue: (C) is correct if you require both statements in combination; based on the rest of your post, I''m going to assume that you meant that you thought the correct answer should be (D), ...”
May 3, 2012
Stuart Kovinsky posted a reply to Challenge-statistics in the Data Sufficiency forum
“Hi! You seem to have misinterpreted the question as "what is the smallest possible number in the set?", when in fact it''s simply "what is the smallest number in the set?" With (1) alone, there''s no way to determine the actual value of x, y or z, so (1) is insufficient. ...”
May 1, 2012
Stuart Kovinsky posted a reply to Angles in the Problem Solving forum
“Hi! You''d definitely benefit from drawing out a clock on this question (as you would on pretty much any geometry question). Sadly, computer-generating diagrams is not one of my strengths, so we''ll just visualize. Let''s think about where the hands are at 4:20: the little hand is on the 4 ...”
May 1, 2012
Stuart Kovinsky posted a reply to Does this ques represent Complex or Normal GMAT standard? in the Problem Solving forum
“One other thing that''s important to note... while the OG is a good source of questions, it''s generally a horrible source of explanations (especially in math). The OG math explanations tend to be the "how to get 10/10 on your grade 10 math test" solution, rather than the "how to ...”
May 1, 2012
Stuart Kovinsky posted a reply to Confusion with wording of option (2) ? in the Data Sufficiency forum
“Hi, the key word is "any". (2) says that the difference between ANY two factors of n is odd; read ANY as EVERY (they mean the same thing). So, if n=12, then we have lots of pairs of factors that do NOT have an odd difference, e.g.: 3-1=2 4-2=2 6-2=4 and so on... The ...”
May 1, 2012
Stuart Kovinsky posted a reply to Confusion with wording of option (2) ? in the Data Sufficiency forum
“Hi Ronnie, what, exactly, is ambiguous? I''d argue that there''s only one way that it can be properly interpreted (the word "any" is the key to proper interpretation).”
April 30, 2012
Stuart Kovinsky posted a reply to Combinations Problem in the Problem Solving forum
“Hi! You''ve ignored the "of the same size" requirement for each possible package type, which is why you ended up with twice the possibilities.”
April 30, 2012
Stuart Kovinsky posted a reply to Combinations Problem in the Problem Solving forum
“Hi! Let''s start with Step 1 of the Kaplan Method for PS: analyzing the question stem. We''re told that there are 2 different sizes of pad - let''s call them small and large ("s" and "l"). There are also 4 different colours, b, g, y and p. We''re allowed to make 2 ...”
April 30, 2012
Stuart Kovinsky posted a reply to Confusion with wording of option (2) ? in the Data Sufficiency forum
“Hi! As Sanju points out, 6-2 is, in fact even; as is 3-1, another pair of factors of 6. Let''s think about statement (2) some more. How do we get an odd difference between integers? If one is even and one is odd. So, if a number has two odd factors, then we''ll get an even difference. If a ...”
April 30, 2012
Stuart Kovinsky posted a reply to Confusion with wording of option (2) ? in the Data Sufficiency forum
“Hi! There''s nothing ambiguous about (2), it just needs to be read carefully (like all DS statements!). "The difference between ANY two distinct positive factors of n is odd" must mean two things: 1) n only has 2 distinct factors; and 2) those 2 factors are 1 apart. The first ...”
April 30, 2012
Stuart Kovinsky posted a reply to PS: functions - difficult and time consuming one in the Problem Solving forum
“Please repost - large portions of the question are missing. Thanks!”
April 30, 2012
Stuart Kovinsky posted a reply to Does this ques represent Complex or Normal GMAT standard? in the Problem Solving forum
“Like a lot of GMAT challenge questions it may be very hard to solve using number properties but is vastly simplified by picking numbers. n/5 has rem 1. n could be 1, 6, 11, 16, ... (any number ending in 1 or 6) n/7 has rem 3. n could be 3, 10, 17, 24, 31... Since 31 is the first number that ...”
April 29, 2012
Stuart Kovinsky posted a reply to Source Grockit: DS: Inequallity in the Data Sufficiency forum
“Hi! Whenever you see inequalities and variables, alarm bells should go off in your head and your internal warning system should be shouting "DANGER DANGER DANGER!!!" Remember this key difference between equations and inequalities: When you multiply or divide both sides of an ...”
April 29, 2012
Stuart Kovinsky posted a reply to Greensboro County, 75 people in the Problem Solving forum
“Approaching a different way we also see that the question is defective. Let''s call those who own both "b" and those who own neither "n". So, we have: (1) b + n = 1/2(75+35-b) (we subtract the extra b because we want "the amount [which should be "the ...”
April 29, 2012
Stuart Kovinsky posted a reply to Combination Problem : Need Help in the Problem Solving forum
“Hi! The question is actually much easier than you think. Let''s start with a simpler version of the same question: Solving by brute force, we get: Salad/Fish Salad/Chicken Salad/Beef Soup/Fish Soup/Chicken Soup/Beef for a total of 6 possible meals. However, what we''re ...”
April 28, 2012
Stuart Kovinsky posted a reply to Zanco's failure in the Critical Reasoning forum
“If you add the "who patronize Zanco aren''t likely" as you have, then that answer would definitely be a strengthener, since it''s more evidence to support the conclusion. However, a strengthener isn''t necessarily an assumption; for that same reason, if the denial of your choice ...”
April 28, 2012
Stuart Kovinsky posted a reply to Zanco's failure in the Critical Reasoning forum
“Hi again! Your denial of (3) is spot on (some people forget that the opposite of "all don''t" is "at least one does"), but I disagree that the denial actually weakens the argument. Just because 1 person does, in fact, use moral considerations doesn''t make us believe that ...”
April 27, 2012
Stuart Kovinsky posted a reply to Players in a tournament in the Problem Solving forum
“Hi! We have variables in the choices, so we can definitely pick numbers to solve this problem. Let''s pick the smallest numbers we can to keep the question manageable: 6 teams and 4 players per team. Now let''s write out our teams, in accordance with the rules: 1: ABCD 2: DEFG 3: ...”
April 27, 2012
Stuart Kovinsky posted a reply to Probability Strategy in the Problem Solving forum
“Hi! Both solutions are always correct - if you get two different answers, then you must have made a mistake along the way. Here, for example, you''ve miscalculated what you call solution B. In your solution, you only look at the case in which none of them is a 6; however, we also satisfy ...”
April 27, 2012
Stuart Kovinsky posted a reply to Zanco's failure in the Critical Reasoning forum
“As noted above, an assumption is something that MUST be true in order for the conclusion to follow from the evidence. Accordingly, the strength of an assumption must match the strength of the argument. For this reason, avoid EXTREME answers on assumption questions. For this argument to hold, ...”
April 27, 2012
Stuart Kovinsky posted a reply to Zanco's failure in the Critical Reasoning forum
“Hi! An assumption is something that MUST be true in order for the conclusion to follow logically from the evidence. In other words, a conclusion is a missing but necessary piece of evidence. The classic way to identify an assumption is to look for a disconnect, i.e. mismatched terms. This ...”
April 27, 2012
Stuart Kovinsky posted a reply to Main Point - MGMT cat 1 in the Critical Reasoning forum
“Hi! Step 1 of the Kaplan Method for CR: identify the question type A large part of the problem here is that people have misidentified the question; it is NOT asking us to draw an inference. Rather, it''s asking for the main point, or the conclusion of the argument. Remember: an inference ...”
April 27, 2012
Stuart Kovinsky posted a reply to P is a polygon in the Data Sufficiency forum
“Umm.. not to be too picky, but the angles in your hexagon are NOT all equal (the 2 angles of the "pointy bits" are different from the other 4 angles). Any polygon with equal angles is, in fact, cyclical.”
April 27, 2012
Stuart Kovinsky posted a reply to URGENT! Help needed please in the Problem Solving forum
“Good call! How do these questions relate to the GMAT?”
April 27, 2012
Stuart Kovinsky posted a reply to Probability problem in the Problem Solving forum
“Hi! As always, when a common formula applies you should jot it down on your scratch paper. So: probability = # of desired outcomes/total # of possibilities. Total # of possibilities is simply the number of numbers, which is 450 (to count the number of consecutive integers in a set, take: ...”
April 27, 2012
Stuart Kovinsky posted a reply to Venn diagrams and Matrices in the Problem Solving forum
“As Ron said, for 2-set questions, you can use either approach (or the overlapping set formula: True # of objects = total # in group 1 + total # in group 2 + total # in neither group + number in both groups). If you''re getting different answers using different approaches, then you''re making ...”
April 27, 2012
Stuart Kovinsky posted a reply to Can anyone help me figure this one out? in the Problem Solving forum
“Perfect solution, just to clarify a few steps: 3x = sqrt(3)*(x^2)/4 We know that x is positive (since it''s the side of a triangle), so we can safely divide both sides by x to get: 3 = sqrt3 * x/4 Multiplying both sides by 4: 12 = sqrt 3 * x Dividing both sides by sqrt3: ...”
April 26, 2012
Stuart Kovinsky posted a reply to GMAT Prep DS problem in the Data Sufficiency forum
“Hi! We''re not assuming anything (never assume in DS!) - we''re intentionally looking at the most extreme case to see if it''s possible to get a "NO" answer to the question. If Bob overestimates some books, then he''d be under by even less than our extreme possibility, pushing him ...”
April 25, 2012
Stuart Kovinsky posted a reply to Fast way to do this? in the Data Sufficiency forum
“You can use your knowledge of concepts to solve rather than plugging in numbers (although picking numbers is also a great way to go). First, let''s ask ourselves when we''ll get a YES answer to the question. First, we need the sign of the top and bottom to be the same (if the signs were ...”
April 25, 2012
Stuart Kovinsky posted a reply to Carol's B-day in the Data Sufficiency forum
“Ooo, great question, since it gives us the opportunity to apply the most powerful rule known to DS experts across the universe: number of equations vs number of unknowns. Here''s the rule: To solve for a system of n variables, one requires n distinct linear equations. Or, somewhat ...”
April 25, 2012
Stuart Kovinsky posted a reply to GMAT Prep DS problem in the Data Sufficiency forum
“Hi! Bob certainly wouldn''t make it very far in the accounting world (although I think he may have worked for Enron). Let''s start with Step 1 of the Kaplan Method for DS: Analyze the question stem. We know that Bob rounds off book prices to the nearest dollar and want to know if "the ...”
April 25, 2012
Stuart Kovinsky posted a reply to DS: number properties in the Data Sufficiency forum
“We know that: x^n - x^(-n) = 0 or x^n = x^(-n) and we want to find the value for x. Let''s start by analyzing the question stem, something too many test takers fail to do. A negative exponent is the same as 1 over that exponent. In other words: x^(-n) = 1/(x^n) So, we can ...”
April 25, 2012
Stuart Kovinsky posted a reply to Set theory problem. in the Data Sufficiency forum
“Hi, I''m a bit confused about what this has to do with: 1) data sufficiency; and 2) the GMAT! Thanks, Stuart”
April 25, 2012
Stuart Kovinsky posted a reply to Manufacturing DS in the Data Sufficiency forum
“I just want to address this particular concern, since it''s a great question. Whenever you have a term of two variables multiplied together, you no longer have a linear equation (since when you sub in for x or y, you''ll get a squared term). For example, let''s look at this question: ...”
April 25, 2012
Stuart Kovinsky posted a reply to x=the 12th power of an integer? in the Data Sufficiency forum
“Common sense and logic are some of the most underrated GMAT tools; applying "math common sense" to this problem makes it understandable. Let''s agree that neither statement on its own is sufficient and jump right to combination. Since x > 1, we know that statements (1) and (2) ...”
April 25, 2012
Stuart Kovinsky posted a reply to Two models of computers in the Problem Solving forum
“Some good solutions posted already; we can also use the basic work formula for two workers: CT = combined time A = time for worker 1 to do job on its own B = time for worker 2 to do job on its own CT = (A*B)/(A+B) In this case: CT = 9*18/(9+18) = 162/27 = 6 Since it takes 6 minutes ...”
April 25, 2012
Stuart Kovinsky posted a reply to How to solve this the non-differentiation way? in the Problem Solving forum
“Although we don''t normally do so when there are variables in the choices, you can also solve by backsolving. Let''s start by subbing in for B to get: (x - A)^2 + (x - (A + 4))^2 = (x - A)^2 + (x - A - 4)^2 If we Sub in x = A, we get: (A - A)^2 + (A - A - 4)^2 = 0 + 16 Now let''s ...”
April 25, 2012
Stuart Kovinsky posted a reply to median question.. in the Data Sufficiency forum
“Hi! When you have an even number of terms, the median is the average of the two middle terms. Since there are 14 terms in your set, we want the average of the 7th and 8th terms. Since T7 and T8 are both 3, the average is: (3+3)/2 = 6/2 = 3 and, accordingly, the median is still 3.”
April 25, 2012
Stuart Kovinsky posted a reply to GMAT PREP PS Problem in the Problem Solving forum
“Hi Alex! This question has been posted and explained many times. If you do a search on "circle intersect triangle" you''ll find a number of detailed solutions, many of which have very informative diagrams. Happy hunting!”
April 22, 2012
Stuart Kovinsky posted a reply to GMAT PREP PS Problem in the Problem Solving forum
“Excellent solution! My only advice would be to use fractions instead of decimals to minimize the calculations. If x = 4/5(y), then y = 5/4(x) (it''s always just the reciprocal of the fraction on this type of question) and we can quickly convert 5/4(x) to 1.25(x), since the answers are in ...”
April 22, 2012
Stuart Kovinsky posted a reply to Probability Inquiry in the Problem Solving forum
“Hi Ray, I''m not a big fan of the P(A) + P(B) - P(A&B) approach, since as you point out it can get confusing in more complicated situations. If you''re comfortable with the other approaches, I''m not sure why you''d ever use this one. That said, and since you seek understanding (always a ...”
April 22, 2012
Stuart Kovinsky posted a reply to Coin flip questions made easy in the GMAT Math forum
“Hi! I was away for a while, but I am indeed back! You can indeed use that version of the formula for die roll questions.”
April 20, 2012
Stuart Kovinsky posted a reply to GMAT PREP PS question in the Problem Solving forum
“Hi! This question is testing you on the "length of a side of a triangle rule": each side must be greater than the positive difference between the other two sides and less than the sum of the other two sides, or, if we call the sides x, y and z: |y-z| < x < y + z Applying ...”
April 18, 2012
Stuart Kovinsky posted a reply to PS: % in the Problem Solving forum
“Hi! Almost certainly, the quickest way to solve this type of weighted average problem is by plotting the groups and the total on a number line, like this: Group 1 -----x------ Total Avg -----y----- Group 2 in which x and y represent the distance between Group 1 and the average and Group 2 ...”
April 18, 2012
Stuart Kovinsky posted a reply to Rule of 70 question in the Problem Solving forum
“Hi! Since the employee is 32 at the start of her employment, she needs to accumulate 70-32 = 38 "points" to retire. Each year she works she gets 2 points - 1 for working and 1 for getting a year older. So, to determine how many years she needs to work, we simply divide 38 by 2 to ...”
April 18, 2012
Stuart Kovinsky posted a reply to Kaplan:CPR in the Critical Reasoning forum
“We''ve identified that we have a weakening question, so let''s go to step 2 of the Kaplan method for CR: untangle the stimulus. First, it''s essential to identify the restaurateur''s conclusion - I think that part of the problem has been that people haven''t properly figured out what the main ...”
April 15, 2012
Stuart Kovinsky posted a reply to Standard Deviation in DS in the Data Sufficiency forum
“On the GMAT, one is NEVER asked to calculate the SD of a set. However, one might be asked, as in this question, whether it''s POSSIBLE to calculate the SD of a set. In order to determine the SD of a set, you need 2 pieces of information about the set: 1) the number of terms; and 2) the exact ...”
April 12, 2012
Stuart Kovinsky posted a reply to PR 1024 Functions #6 in the Data Sufficiency forum
“Hi! The question makes no sense as you''ve posted it. Unfortunately, p164 is omitted from that preview of the book, so there''s no way to check the actual question. Here''s how the question likely reads in order for (D) to be correct: If f(x) = x^2 + x for all values of x, what''s f(y)? ...”
April 12, 2012
Stuart Kovinsky posted a reply to Inequalities with Absolute value in the Problem Solving forum
“Hello! If a does in fact equal 1.75, then of course |1.75| < 2 and (I) must be true. Are you sure that you''ve accurately reproduced the question/answers? We can solve very quickly just by plugging in a=1.75 to each statement: (I) |1.75|<2... Is 1.75 < 2? YES, therefore TRUE ...”
April 12, 2012
Stuart Kovinsky posted a reply to probability. in the Problem Solving forum
“Hello! This is a non-GMAT question for 2 reasons. First, there are no answer choices. Second, GMAT probability always deals with INDEPENDENT events - here, not only does the question not specify that the events are independent, but it also implies that they could be dependant. After all, if ...”
April 12, 2012
Stuart Kovinsky posted a reply to probability. in the Problem Solving forum
“Hello! I see that you''re fairly new to the forums, so just a friendly tip - please post your questions in the right place! This is the problem solving forum, but this is a data sufficiency question. Data sufficiency is a test of your knowledge of concepts, NOT your ability to do lots and ...”
April 12, 2012
Stacey Koprince posted a reply to Changes in GMAT - Has Mgmat test adapted to these changes ?? in the Ask a Manhattan GMAT representative forum
“They have stripped out only US-centric idioms. (When they first made the announcement, they said idioms in general, but they later clarified that they only took out US-centric idioms.) They have not provided a list of which idioms they consider US-centric, but the list in our SC guide does not ...”
January 31, 2012
Stuart Kovinsky posted a reply to Word Problem: Kaplan WB in the Problem Solving forum
“Hi! It doesn''t say that he used all of his bills, just that he received no change from the purchase. In other words, he couldn''t have bought an item that cost $8, because then he would have received at least$2 in change. For example, if you walked into a store with \$200 in your wallet, ...”
January 26, 2012
Stacey Koprince posted a reply to Neanderthals had a vocal tract in the Sentence Correction forum
“I don''t post on the forums any longer but will answer this one quickly. :) B is the official answer. E is incorrect because it has a pronoun issue: the subject of the first clause is "vocal tracts" and the "they" pronoun later in the sentence is also a subject pronoun, ...”
January 9, 2012
Stuart Kovinsky posted a reply to King Alfred in the Sentence Correction forum
“As always, great explanation by Ron! Another reason we can eliminate (A) is improper verb tense. In the non-underlined portion of the sentence we have the simple past used to refer to an action taken in 893. Since the action in the first part of the sentence refers to 886, it should use an ...”
December 11, 2011
Stuart Kovinsky posted a reply to sets/venn diagram problem in the Problem Solving forum
“rethinking!”
December 4, 2011
Stuart Kovinsky posted a reply to Eating contest in the Problem Solving forum
“Here''s a good rule to remember for the GMAT: When a question asks you to minimize one thing, you want to maximize something else; when a question asks you to maximize one thing, you want to minimize something else. Here we''re asked to minimize the number of people who eat all 3 meals; to ...”
December 4, 2011
Stuart Kovinsky posted a reply to Modulus PS in the Problem Solving forum
“We can solve this problem by picking numbers to eliminate 4 of the 5 choices. First, let''s pick a big positive number. If x=10, we get: 10/10 < 10, which is certainly true. Therefore, x could be 10. Accordingly, we can eliminate (c) and (d). We can now either pick another number ...”
December 4, 2011
Stuart Kovinsky posted a reply to Coin flip questions made easy in the GMAT Math forum
“That question asks you to solve for the standard deviation of a set; since the GMAT never asks you to solve for standard deviation, I have no idea why anyone would even want to solve that problem!”
November 21, 2011
Stuart Kovinsky posted a reply to Tough and confused parallelism - need the help of expert in the Sentence Correction forum
“Hi, none of the answers are very good; it''s very helpful for the BTG community to know the source of all of your questions (so you should always include the source when you make a new post) - where does this one come from?”
November 21, 2011
Stuart Kovinsky posted a reply to Rivaling the pyramids of Egypt- Modifier Issue in the Sentence Correction forum
“Hi! B makes the same mistake as do C, D and E - they all have a giant misplaced modifier. If you recognize that issue (and it''s one of the "big 5" grammar issues tested on the GMAT, so you need to be a Master of Modification by test day), then this becomes a 15-30 second question. ...”
November 21, 2011
Stuart Kovinsky posted a reply to vinegar and water in the Data Sufficiency forum
“Hi! This question is a great illustration of the most powerful rule to remember for data sufficiency: number of equations vs number of unknowns. Here''s the "official" wording of the rule: Put more simply, if you have the same number of linear equations as you have variables, ...”
November 21, 2011
shovan85 posted a reply to MArx in the Critical Reasoning forum
“Consider that, you do not know who is Marx (if he is a German or Not) and you do not know what is the base for someone to be idealist. Now see between the two options you are getting confused with. I guess you can Infer the correct option now :)”
October 12, 2011
Stacey Koprince posted a reply to MEaning based SC. ! in the Sentence Correction forum
“Someone asked me to weigh in on this - I don''t normally post on the forums, but I will on this one. :) Brian is absolutely right that the directions make no mention of needing to preserve the original meaning (and, of course, sometimes the original meaning is actually illogical or ambiguous and ...”
October 6, 2011
Stacey Koprince posted a new topic called More news from GMAC on idioms in the GMAT Strategy forum
“Hi, all I just posted this in the comments section of my article, but it''s important enough that I wanted to add it here. Larry just emailed me again about the idioms issue. Two very important things (the first from Larry, the second from me): (1) Larry just got back into the office and ...”
September 23, 2011
Stacey Koprince posted a new topic called GMATPrep for the Mac in the GMAT Strategy forum
“Hey, all, one other little tidbit I wanted to share from the GMAC conference - they''re (finally!) going to come out with a version of GMATPrep for the Mac! It won''t, however, be until the next version of GMATPrep launches, in April of 2012. So - no real news for people taking the test before ...”
September 21, 2011
Stuart Kovinsky posted a reply to GUESS in the Problem Solving forum
“Hi! This is a very strange question - did you make it up? You''ll never see something in this format on the GMAT. First, answer (D) makes no sense - points cannot be parallel (the concept of parallelism doesn''t apply to points). Similarly with (E) - what does "on different ...”
August 23, 2011
shovan85 posted a reply to Account in the Sentence Correction forum
“Its E. E is not only stating the correct meaning (Using....) but also it is concise (in both x and y). There is a great video tutorial by Ron Purewal available in the below link... http://www.manhattangmat.com/thursdays-with-ron.cfm Scroll to Sep 23 2010.”
July 8, 2011
shovan85 posted a reply to Area in the Problem Solving forum
“http://s2.postimage.org/1uh3e3d2c/untitled.jpg”
July 8, 2011
shovan85 posted a reply to Area in the Problem Solving forum
“The center is at (0,6). The circle formed around this center has to be symmetrical against the Y-axis. The distance between the two points intersecting X-axis is 16. So, we can say the length of the chord is 16. The distance of any of the points from origin (0,0) is 8 as the circle is ...”
July 7, 2011
Stacey Koprince posted a reply to MGMAT Problem (Advanced Quant) in the Data Sufficiency forum
“Yes, we definitely keep track so that we can fix errors in future printings, and we also post errata lists online so that you can check to see whether something is already a known error. I don''t think we have an errata list up for this book yet, but we will soon. If you spot errors in any of our ...”
June 16, 2011
Stuart Kovinsky posted a reply to Average Speed of Bus in the Data Sufficiency forum
“Hi, you can''t use that approach on this question, since it involves assuming facts that aren''t in evidence. From (1) we can conclude that for the first half of the time, the average rate is 50 mph. From (2) we can conclude that the rate for the first half of the distance is two times the ...”
June 13, 2011
Stuart Kovinsky posted a reply to Box office receipts in the Critical Reasoning forum
“Hi, "box office receipts" always refers to revenue (at least in North American colloquial English, which is what the GMAT uses). As Mitch points out, if it referred to the number of movies then the stimulus is self-contradictory, which can never happen on inference questions.”
June 13, 2011
Stuart Kovinsky posted a reply to At a certain company in the Data Sufficiency forum
“Hi, there''s no need for the original question to mention that, because it''s implied by default. If the question maker wanted there to be no people who belong to the "neither" category, then THAT would have had to be explicitly stated. For example, if you were to say: "some ...”
June 10, 2011
Stuart Kovinsky posted a reply to PROBLEM SOLVING in the Problem Solving forum
“Hi! The GMAT is in part about math, but it''s also in part about speed. Without any doubt the quickest way to solve this problem, and many problems in which you''re given rules about how variables behave but no actual values, is by picking numbers. m/6 has rem 2, so let''s pick m=8 n/6 has ...”
June 10, 2011
Stuart Kovinsky posted a reply to Sets sum in the Problem Solving forum
“Many of the questions with which you''re practicing have been previously discussed on this board. The BTG search tool is very useful. Here are a couple of threads discussing this question: edit: typo!”
June 10, 2011
Stuart Kovinsky posted a reply to Earth in the Critical Reasoning forum
“Why do you think B must be true in order for the conclusion to follow? If you post your reasoning, we can give you a better answer. There are two general reasons why B isn''t an assumption. First, it''s too extreme. Does every river on earth have to have roughly the same level of salt for ...”
June 10, 2011
Stuart Kovinsky posted a reply to triangles in the Problem Solving forum
“Yup! Two objects intersect if they have at least one point in common.”
June 10, 2011
Stuart Kovinsky posted a reply to circumf of circle in the Problem Solving forum
“Great solution! A lesser known formula for the area of a square is: area = (diagonal^2)/2 which is derived from the Pythagorean theorem (using 45/45/90 ratios).”
June 9, 2011
Stuart Kovinsky posted a reply to triangles in the Problem Solving forum
“Hi, here''s a link to another post with pretty diagrams: [url]http://www.beatthegmat.com/number-of-points-a-circle-can-intersect-a-triangle-t76683.html[/url] If you search "circle intersect triangle" on-site you''ll find a number of threads discussing this question.”
June 9, 2011
Stuart Kovinsky posted a reply to integers in the Problem Solving forum
“Hi Divya, while I appreciate your enthusiasm for getting your questions posted as quickly as possible, I''m sure that I speak for all BTG users when I say we''d appreciate it even more if you''d slow down a bit and proofread your posts - there are so many typos and abbreviations that it''s almost ...”
June 9, 2011
Stuart Kovinsky posted a reply to Anybody - Shortest/fastest way to solve this one? in the Problem Solving forum
“Hi, just because it''s true that the mean=median for all arithmetic progressions doesn''t mean that it''s true that mean won''t equal median for all other sets; there''s just no fixed rule for other sets. So, if your set is created by an AP you know that mean=median; if you have another set ...”
June 9, 2011
Stuart Kovinsky posted a reply to 3 Alligations and Mixtures Sums in the Problem Solving forum
“I''m curious - what''s the source of these questions? I''m guessing an Indian site somewhere due to the language (and currency) used. Be very wary of using questions that aren''t worded similarly to those on the actual GMAT - you''re not training yourself for real test questions. So, while the ...”
June 8, 2011
Stuart Kovinsky posted a reply to DS - SETS in the Data Sufficiency forum
“Cans is dead on - nowhere does it say that every resident belongs to at least one fitness club, so we can''t make that assumption. It''s actually very rare for 3-set questions on the GMAT to have a "none" component, which is why the formula doesn''t usually worry about that possibility; ...”
June 7, 2011
Stuart Kovinsky posted a reply to Tough Kaplan in the Data Sufficiency forum
“Hi, there''s absolutely no reason why 2x couldn''t be 0; after all, 0 is even. However, considering x=0 for statement (1) doesn''t change the answer to the question. Remember, we need to get a "definite yes" or "definite no" for a statement to be sufficient. Let''s look ...”
June 7, 2011
Stuart Kovinsky posted a reply to Weaken Question: in the Critical Reasoning forum
“I got a PM asking me to post on this thread, so I will, although others have done an admirable job explaining why B is correct and why C and E aren''t. One important factor in your CR success will be how well you understand the scope of the argument. Since the most common trap in CR is ...”
June 6, 2011
Stuart Kovinsky posted a reply to assumption question in the Critical Reasoning forum
“Hi, you''re right, we don''t need the rates to be identical - that''s exactly why the language of B ("the rate.. IS SIMILAR to the rate...") is perfect for this question. If B had said "the rate... is identical to the rate..." then it would have been overly precise and you ...”
June 5, 2011
Stuart Kovinsky posted a reply to Simplify.. in the Problem Solving forum
“You will NEVER see that language on the GMAT - so don''t worry about it. Pretty much the only time you''ll see "of" and need to translate into math will be with fractions or percents, e.g. "What number is 20% of 90?"; or "What number is 1/5 of 90?" ...”
June 5, 2011
Stuart Kovinsky posted a reply to assumption question in the Critical Reasoning forum
“What''s the source? If this were an inference question, then D would be correct; however, since this is an assumption question, B is definitely the right answer. As GMATMadeEasy notes, D is just a summary of the analyst''s conclusion, whereas an assumption is a missing but necessary piece of ...”
June 5, 2011
Stuart Kovinsky posted a reply to LSAT CR Question in the Critical Reasoning forum
“Why oh why will no one listen to the advice given almost universally by the experts: The LSAT is NOT a good source of practice for the GMAT. This question, for example, is a "principle" question - one that you will almost certainly never see on the GMAT. The LSAT has many different ...”
June 4, 2011
Stuart Kovinsky posted a reply to SC -help!! in the Sentence Correction forum
“As Arpita explains, E is the best of the lot, but even E leaves a lot to be desired (E makes it sound like sunspot cycles occur on Earth, which is non-sensical - the Earth doesn''t have sunspots!). What''s the source of the question?”
June 4, 2011
Stuart Kovinsky posted a reply to boldface in the Critical Reasoning forum
“Hi! A great way to approach bolded statement question is to roadmap the stimulus just as you would a reading comp passage, treating each sentence like a mini-paragraph. Just like reading comp, don''t roadmap for content - roadmap for structure. If you have a roadmap of the structure of the ...”
June 4, 2011
Stuart Kovinsky posted a reply to OG Quant supplement 2nd edition # 42 in the Data Sufficiency forum
“Let''s examine statement (2) conceptually rather than with equations. (2) tells us that Y is 10 more than X. From the original, we know that Y is greater than 110% of X. Since Y is greater than 110% of X, we know that Y is more than 10% more than X. Putting that information together, we ...”
June 4, 2011
Stuart Kovinsky posted a reply to Anybody - Shortest/fastest way to solve this one? in the Problem Solving forum
“Hi, we can solve this either via algebra or picking numbers. Let''s try picking numbers. All we know is that y>6, so let''s pick y=7. We now know that the mean is 7+3=10. So: Avg = (sum of terms)/(# of terms) 10 = (x + 7 + x+7 + x-28 + 7x + 14)/6 60 = 10x + 28 - 28 60 = 10x 6 = ...”
June 4, 2011
Stuart Kovinsky posted a reply to Work in the Problem Solving forum
“Hi, there''s a very simple formula to solve 2-worker problems: Combined Time = (t1*t2)/(t1+t2) So, we simply have: CT = (2*3)/(2+3) = 6/5 That formula is derived from the more standard work formula: 1/(combined time) = 1/t1 + 1/t2+ 1/t3 + ... in which t1, t2, t3 and so on are ...”
June 4, 2011
Stuart Kovinsky posted a reply to Is Right angle triangle? in the Data Sufficiency forum
“You''re 100% right! That will teach me not to read all the information carefully!”
June 2, 2011
Stuart Kovinsky posted a reply to Is Right angle triangle? in the Data Sufficiency forum
“I just wanted to address this solution, since it makes a common mistake for which test takers need to be watchful. Remember, when solving an isosceles triangle you can''t assume which angles are equal and which one is different. Another perfectly acceptable solution to the problem is: x + 2z ...”
June 2, 2011
Stuart Kovinsky posted a reply to A critical Doubt in the Data Sufficiency forum
June 1, 2011
Stuart Kovinsky posted a reply to A critical Doubt in the Data Sufficiency forum
“Just the fact that they make that statement is an indication of how poorly they understand the GMAT. What that really says is "STAY AWAY FROM OUR MATERIAL!!"”
June 1, 2011
“Each option should be acceptable on the GMAT (and in regular life).”
May 31, 2011
Stuart Kovinsky posted a reply to tenses :) in the Sentence Correction forum
“Hi, this seems like a poorly worded question, since as you point out "persisting" isn''t parallel to "comprise". However, (2) is definitely wrong, since particles "persist", not "persists" (particles are plural, so we need the plural version of the ...”
May 31, 2011
Stuart Kovinsky posted a reply to integer problem in the Data Sufficiency forum
“Hi, 1.5 + 5 = 6.5, not 2. Since 6.5 isn''t an integer, x=1.5 is not permitted for statement one. Here''s a good rule to remember regarding integers: whenever you add, multiply or subtract two integers, the result will always be an integer. Looking at (1): x + 5 = int x = int - 5 ...”
May 31, 2011
Stuart Kovinsky posted a reply to Is Right angle triangle? in the Data Sufficiency forum
“Let''s answer the question using minimal math, relying on our general knowledge of triangle rules. Rephrasing the question: is one of the angles of triangle ABC 90 degrees? 1) two of the angles are equal. Neither of those angles could be 90 (since we only have a total of 180 degrees), but we ...”
May 31, 2011
Stuart Kovinsky posted a reply to A critical Doubt in the Data Sufficiency forum
“Hi, if each statement seems sufficient but gives a different answer, there are two possibilities: 1) you have made a mistake (i.e. they''re not both sufficient); and 2) it''s not a proper GMAT question. On the actual GMAT, the two statements will NEVER contradict one another. When (D) ...”
May 31, 2011
Stuart Kovinsky posted a reply to Exponents in the Problem Solving forum
“Hi, that''s 100% correct. Since we can pick values that satisfy both the original inequality (which we know is true) and choice (E), we''ve proven that choice (E) COULD be true. Since it COULD be true, it''s the wrong answer to a CANNOT be true question.”
May 30, 2011
Stuart Kovinsky posted a reply to Sequence in the Problem Solving forum
“Hi! This question is, undoubtedly, the most often posted question on this site. If you do a search on h(100) you''ll find many many explanations. Here''s one on which I contributed: [url]http://www.beatthegmat.com/gmat-prep-number-properties-t8649.html?highlight=100[/url] and there are ...”
May 29, 2011
Stuart Kovinsky posted a reply to OG PS 98 in the Problem Solving forum
“Hi, here''s a previous thread that discusses the question, including some geeky trivia provided by yours truly! [url]http://www.beatthegmat.com/formulas-on-a-scale-that-measures-the-intensity-of-a-certai-t9917.html[/url]”
May 29, 2011
Stuart Kovinsky posted a reply to Exponents in the Problem Solving forum
“Hi! We know that y^4 must be non-negative. So, from the original inequality we know that x^3 must be positive. Accordingly, we can conclude that x is positive. With that in mind, since we want an answer that CANNOT be true, let''s look for a choice that requires x to be non-positive. A) ...”
May 29, 2011
Stuart Kovinsky posted a reply to Voting Districts in the Problem Solving forum
“Hi! Here''s a thread in which I solved this question via backsolving: [url]http://www.beatthegmat.com/gprep-t13262.html[/url] Here''s another thread that has a nice algebraic solution: [url]http://www.beatthegmat.com/problem-from-the-mba-com-practice-test-1-t13457.html[/url] Enjoy!”
May 29, 2011
Stuart Kovinsky posted a reply to Distance in the Data Sufficiency forum
“Hi! This question has been addressed before and the answer is E, not A. Here''s one thread that explains why: [url]http://www.beatthegmat.com/number-line-x-y-and-z-t23333.html[/url]”
May 29, 2011
Stuart Kovinsky posted a reply to Speed&Distance in the Data Sufficiency forum
“Hi! This question is a perfect place for our data sufficiency hero, "number of equations vs number of unknowns Man", to make an appearance. Starting by analyzing the stem: we know that distance = rate * time. We have the distance and we want to solve for the time. Accordingly, ...”
May 29, 2011
Stuart Kovinsky posted a reply to Sum of Integers in the Problem Solving forum
“Hi! This question has been posted quite a few times. Here''s one discussion: [url]http://www.beatthegmat.com/gmat-numbers-t10420.html[/url] The "Search Beat the GMAT" function (top right of the page) is very useful and it''s always worth putting in a few keywords from your ...”
May 29, 2011
Stuart Kovinsky posted a reply to Probability in the Problem Solving forum
“Hi again Akansha! Before we start, I want to point out a problem with this particular question. Nowhere does it say that a question has an equal chance of being true or false. Accordingly, it''s impossible to answer (and could never appear on the GMAT without that information). We''ll go ahead ...”
May 29, 2011
Stuart Kovinsky posted a reply to Average Length in the Problem Solving forum
“Hi Akansha! Let''s start by analyzing the question stem. We know that: 5 pieces Average length 124cm, so sum = #*avg = 5*124cm = 620cm Median length 140cm; odd number of terms, so the middle term must be 140. Our goal: to find the LONGEST POSSIBLE length of the SHORTEST piece of wood. ...”
May 29, 2011
Stuart Kovinsky posted a reply to Actual GMAT Quant tougher than Kaplan?? in the Ask a Kaplan representative forum
“Hi Kailash, glad to hear that things went well; that, of course, is the most important thing. Standard deviation is definitely testable by the GMAT (as are other measurements of sets, such as median, mode and range); what I''ve never heard of, however, is a question that actually required you ...”
May 29, 2011
Stuart Kovinsky posted a reply to Actual GMAT Quant tougher than Kaplan?? in the Ask a Kaplan representative forum
“Hi Calvin! Did you actually see a question on the GMAT that required you to use the standard deviation formula? I''ve never heard of that happening before, so I''d be very surprised if that were the case! As Eli said, we do cover standard deviation (and those other topics that you mentioned) in ...”
May 29, 2011
“Hi! The majority of applicants to B-school don''t have a science background - and GMAC knows that. So, why does it include so many natural science passages on the exam? To test whether you can handle new information. If you''re thrown off by the style of writing and general vocabulary ...”
May 29, 2011
Stuart Kovinsky posted a reply to Grainco in the Critical Reasoning forum
“Hi! In explain questions, the stimulus is usually a set of surprising facts - there seems to be a discrepancy, contradiction or anomalous behaviour. Our job is to find the answer that, if true, resolves the issue. We start by summarizing the situation: Grainco''s biggest selling product ...”
May 29, 2011
Stuart Kovinsky posted a reply to Lsat RCs Vs OG Rcs in the Reading Comprehension forum
“Hi! I''m not sure that I understand the fascination with using LSAT questions to practice for the GMAT. Yes, there are some similarities between the two exams, but there are also a lot of differences. Many people like to use LSAT questions for practice because they''re perceived as more ...”
May 29, 2011
Stuart Kovinsky posted a reply to Integer in the Data Sufficiency forum
“Hi! Let''s start by analyzing the question stem. If sqrt(n) is a positive integer, then n is a perfect square, e.g. 1, 4, 9, 16, ... We want to know the exact value of n. (1) we know that sqrt(n) is an integer between 1 and 5. So, sqrt(n) could be 2, 3 or 4. Each of those gives us a ...”
May 29, 2011
Stuart Kovinsky posted a reply to Integer in the Problem Solving forum
“Picking numbers and elimination is a great way to tackle roman numeral questions - amar covered that approach very well. On test day, that would likely be the best approach. Let''s take a step back, however, and go into "review mode", something you should do for every question you ...”
May 29, 2011
Stuart Kovinsky posted a reply to Question 1 in the Problem Solving forum
“Here''s a link to another discussion of this question: [url]http://www.beatthegmat.com/gmat-expressions-t10416.html[/url]”
May 29, 2011
Stuart Kovinsky posted a reply to GMAT Prep SC - Dr Ruth R Faden in the Sentence Correction forum
“Hi, GMAT grammar/style isn''t always different from standard grammar/style (in fact, it''s supposed to be the same). By the standards of North American idioms, "for doing" will pretty much never be correct (I''m pretty sure you can come up with a counter-example to any rule of English ...”
May 26, 2011
Stuart Kovinsky posted a reply to GMAT Prep SC - Dr Ruth R Faden in the Sentence Correction forum
“Hi all! E is definitely the best choice. While "it" is technically ambiguous (both the White House and the Federal Advisory Committee of experts are possible antecedents), none of the other choices provide a better alternative. Remember, while the GMAT prefers non-ambiguous ...”
May 26, 2011
Stuart Kovinsky posted a reply to prep test question in the Sentence Correction forum
“Hi! We can quickly eliminate D and E - "both" should be modifying "reflect", so putting reflects after both messes up the sentence. C is also out - "the extent of poor currency exchange rates keeping" is far too awkward. A is also poorly structured. Since ...”
May 26, 2011
Stuart Kovinsky posted a reply to Probability Question in the Problem Solving forum
“Sure! Let''s use a very common GMAT probability question type: coin flips. Whenever you see "at least" or "at most" in a question, you''re dealing with multiple scenarios. Here, for example, we want "at least 1 head" out of 5 flips, so acceptable results are: ...”
May 26, 2011
Stuart Kovinsky posted a reply to DS: Packing Boxes in the Data Sufficiency forum
“Sure! When we say that two items are in a constant ratio, we mean that one is a multiplier of the other. For example, if: x/y = 2/3 we can also express the relationship as: 3x = 2y by cross multiplying by the denominators. However, if we don''t have a simple "x/y" on the ...”
May 26, 2011
Stuart Kovinsky posted a reply to Probability Question in the Problem Solving forum
“Great question! The "one-minus" method is most useful on multiple scenario questions in which there are more scenarios that we want than we don''t want. The question will often have "at least" or "at most" in it, indicating that there are multiple possibilities ...”
May 25, 2011
Stuart Kovinsky posted a reply to GMAT Prep in the Data Sufficiency forum
“Hi, there''s an infinite number of lines with that slope. For example: y = (-1/10)x + 1 y = (-1/10)x + 2 y = (-1/10)x + 3 and so on.... Each of those lines is parallel, but crosses the y-axis in a different spot.”
May 25, 2011
Stuart Kovinsky posted a reply to DS: Packing Boxes in the Data Sufficiency forum
“Hi, (P+10)/P is a ratio, but it''s not a constant ratio; in other words, the value of the ratio changes dependent on the value of P. You''re dead on for (2)!”
May 25, 2011
Stuart Kovinsky posted a reply to A tough one on DS in the Data Sufficiency forum
“Hi! Here''s another thread with some detailed explanations of the question: [url]http://www.beatthegmat.com/median-question-t8140.html[/url]”
May 23, 2011
Stuart Kovinsky posted a reply to DS Question in the Data Sufficiency forum
“Good catch! Remember, math wording is very precise - moving one important word around can completely change the meaning of the question. If the question had read: then we''d have: y = 2.1x The only way we can get y > 2.1x is if the question had read: or”
May 23, 2011
Stuart Kovinsky posted a reply to Probability in the Problem Solving forum
“Hi! This is a truly bizarre question - what''s the source? In any case, it can be solved fairly quickly if you can actually decipher it and understand a few underlying concepts. First, we note that 6^k will be even for all positive values of k. Since 678463 is odd, if k is positive then ...”
May 23, 2011
Stuart Kovinsky posted a reply to Speed Problem in the Problem Solving forum
“Hi, please always post both the source of your question and the answer choices. This question is tailor-made for picking numbers, but because you haven''t included the choices we can''t demonstrate that approach for you.”
May 21, 2011
Stuart Kovinsky posted a reply to Function in the Problem Solving forum
“What''s the source of this question? An old GMAT paper test? Or is it not even from the GMAT? For those of you reading this question and incredibly confused, I wouldn''t sweat it - it''s unlikely you''ll see anything similar on test day. You certainly aren''t expected to know any trig for the ...”
May 21, 2011
Stuart Kovinsky posted a reply to Quick way to calculate square root of large number? in the GMAT Math forum
“Before this gets way out of hand, something important to note: the GMAT never requires you to do crazy calculations to solve questions. GMAC knows that, in real life, people have calculators (or computers, or accounting departments) to do hard math and you''re not being tested on whether you''re a ...”
May 20, 2011
Stuart Kovinsky posted a reply to Bob Wilber in the Sentence Correction forum
“Hi, based on the original sentence, it is still happening - that''s exactly why we use has. Unless there''s an egregious error in the original, we should take the original to be an accurate picture of the author''s intended meaning. Since the author says "has ever come", the author ...”
May 18, 2011
Stuart Kovinsky posted a reply to probability in the Problem Solving forum
“Hi, the problem is that you''re making assumptions based on information that you don''t have - a practice that will get you in a lot of trouble during the GMAT. Here are some things we don''t know: are all 100 tickets for the same lottery, or is each one for a separate lottery; is there ...”
May 18, 2011
Stuart Kovinsky posted a reply to If (a – b)c < 0, which of the following cannot be true? in the Problem Solving forum
“Anurag answered Vinni''s original question regarding the explanation, but I want to discuss a super-fast way to solve this particular problem. It''s often quicker to solve number property questions by focusing on the concepts underlying the question rather than by doing a whole lot of math. ...”
May 18, 2011
Stuart Kovinsky posted a reply to road in the Sentence Correction forum
“Hi, D is definitely not the correct choice. "not as hard as" needs to be followed by a noun, not an action; the usage of that phrase in D is incorrect. For example, we could say: Bob''s head is not as hard as Fred''s; but we can''t say: Bob''s head is not as hard as to ...”
May 18, 2011
Stuart Kovinsky posted a reply to probability in the Problem Solving forum
“Hi, since each ticket has a 50% chance of winning, we must treat each as an independent event; nowhere does the question suggest otherwise. Since there''s a 50% chance of winning (and, accordingly, a 50% chance of losing), we can treat this just as we would the following coin flip problem: ...”
May 18, 2011
Stuart Kovinsky posted a reply to Aristotle SC in the Sentence Correction forum
“When you compare costs, you use less. For example: The sweater costs less than the pants. When you compare the prices of two items, you use lower. For example: The price of the sweater is lower than the price of the pants. Remember, when it comes to idioms, the rules don''t have to ...”
May 17, 2011
Stuart Kovinsky posted a reply to Aristotle SC in the Sentence Correction forum
“I got a PM asking me to reply to this question, so I''ll add my input. Here it is: the other posters have it dead on! Even though price may seem to be non-countable, idiomatically we use "lower" and "higher" with price. Further, since we use "you" in the first ...”
May 17, 2011
Stuart Kovinsky posted a reply to The concert having been finished and the audience having fil in the Sentence Correction forum
“Grammatically it''s fine - stylistically it''s inferior to C. In sentence correction, there''s a checklist of three things to consider: 1) grammar; 2) meaning (i.e. we need to preserve the author''s intended meaning); and 3) style. So, if you have more than 1 choice that''s both ...”
May 16, 2011
Stuart Kovinsky posted a reply to 24/sqr3 in the Problem Solving forum
“Great explanation! To go one step further, what Maaj did is called "rationalizing the denominator"; it''s considered bad form in math to leave an irrational number (e.g. a root) in the bottom of a fraction. Accordingly, on the GMAT you''ll almost never see a root in the denominator ...”
May 16, 2011
Stuart Kovinsky posted a reply to prep 1 in the Problem Solving forum
“Hi! Since each can of frozen orange juice gets mixed with 3 cans of water, we know that 1 can of concentrated OJ makes: 12oz + 3*12oz = 12oz + 36oz = 48oz of orange juice. We want a total of 200*6oz = 1200oz of orange juice. So, to find the number of cans we need, we simply divide the ...”
May 16, 2011
Stuart Kovinsky posted a reply to MGMAT- PS in the Problem Solving forum
“I''ll let someone else do the math on this one - I just want to discuss it from the viewpoint of strategic elimination. The question is: If we understand the question, we can actually eliminate 3 of the 5 choices without even looking at the math. First, let''s compare (A) and (B). ...”
May 16, 2011
Stuart Kovinsky posted a reply to MGMAT- PS in the Problem Solving forum
“For the algebraphiles in the audience: A = 2*(B/100)*C A = 2BC/100 (which is trap answer (A)). Our actual question: what is A% of C? What is 2BC/100 % of C? 2BC/100 % of C = (2BC/100)/100 * C = 2BC/10000 * C = BC/5000 * C = B(C^2)/5000”
May 16, 2011
Stuart Kovinsky posted a reply to MGMAT- PS in the Problem Solving forum
“Took me 4 reads to figure out what the question actually meant! Curse question writers who use "a" as a variable in word problems. Rewriting the question using caps (and adding a space so that "band" reads "b and" - that one really confused me too!): We see ...”
May 16, 2011
Stuart Kovinsky posted a reply to New items developed in the Sentence Correction forum
“I think they''re all bad - what''s the source? If it''s 1000 SC, then let me stop you right there - don''t do those questions, they''re riddled with errors and inconsistencies. If I were constructing the sentence, I''d say: Until someone confirms that this is an actual GMAT question, I ...”
May 16, 2011
Stuart Kovinsky posted a reply to GMAT Prep SC - although impoved efficiency in the Sentence Correction forum
“What''s the source? I''d have definitely gone with A over B. The first thing I noted about B was the use of the passive voice: "demand will be stimulated" is passive, while "it will stimulate demand" is active. It''s very rare for the GMAT to choose a passive construction ...”
May 16, 2011
Stuart Kovinsky posted a reply to CR: Resolve Paradox in the Critical Reasoning forum
“Hi, I''m not sure who "800 Test Prep" is, but this is a poorly constructed question. As noted by a couple of other posters, E explains only part of the issue - and only explains that part partially. E may explain why those stations aren''t going under, but just because they get ...”
May 16, 2011
Stuart Kovinsky posted a reply to The concert having been finished and the audience having fil in the Sentence Correction forum
“Hi, here''s something to know about the GMAT - it was traumatized by the passive voice as a child. Accordingly, the GMAT hates and fears constructions with the verbs "been" and "being"; when you see a sentence written with one of those verbs, it''s almost always wrong. ...”
May 16, 2011
“Hi, the two sentences are essentially the same. The GMAT will never present two such similar choices and force you to choose between them.”
May 16, 2011
Stuart Kovinsky posted a reply to GMAT Prep SC - new genetic evidence in the Sentence Correction forum
“Hi, we can quickly narrow it down to D and E on the basis of parallelism. We have "to revamp..., [to] institute..." as the first two items in our list, so we need "[to] create" as the third item. (The "[to]" is implied throughout the list.) We use the infinitive ...”
May 14, 2011
Stuart Kovinsky posted a reply to Parallel SC in the Sentence Correction forum
“The GMAT is the environmental protector of the verbal world - when in doubt, reduce reduce reduce. If an idea is clearly expressed in two answer choices and one of those choices uses fewer words, then the shorter choice will be correct. The extra "and" that you propose serves no ...”
May 14, 2011
Stuart Kovinsky posted a reply to Introduce Yourself in the Introductions forum
“Hmmm.. I thought only people from Georgia said "y''all"! :D Good luck in your studies.”
May 14, 2011
Stuart Kovinsky posted a reply to At present the Hollywood Restaurant has only standard-height in the Critical Reasoning forum
“Hi, let''s look at the exact wording of the question stem: and D: Does the argument itself give us reason to believe that D is true? Definitely not, since there''s no mention of anything related to D. So, D can''t be the right answer to this question. However, if the question ...”
May 14, 2011
Stuart Kovinsky posted a reply to princeton DS in the Data Sufficiency forum
“Hi, by far, the most powerful rule to remember in DS is the "number of equations/number of unknowns rule". Here''s the basic rule: If you have the same number of distinct, linear, equations as you have unknowns, you can answer any question about the system. Understanding this ...”
May 13, 2011
Stuart Kovinsky posted a reply to Remainder and 1 in the Problem Solving forum
“Hi, first thing to note is that if you''ve reproduced the question correctly, that statement is actually sufficient to answer the question. Q: is (k+5)/5 an integer? As with many DS questions, we can make our lives easier by simplifying the question. Let''s break up the fraction: Is k/5 ...”
May 13, 2011
Stuart Kovinsky posted a reply to At present the Hollywood Restaurant has only standard-height in the Critical Reasoning forum
“Hi! the author''s main support for increased profits is that people who sit at the stools/high tables typically take less time to eat. However, in this specific case, the whole reason that many of the diners attend the restaurant is to look for and observe celebrities. Do we expect these ...”
May 13, 2011
Stuart Kovinsky posted a reply to price in the Problem Solving forum
“Hi! This question is waaaay too ambiguous for the actual GMAT (what do consumption/expenditure actually mean?), but we understand the general thrust, which is a concept that the GMAT definitely tests. In the future, please make sure you include the answer choices and the source of every question ...”
May 13, 2011
Stuart Kovinsky posted a reply to Weighted Average Problem in the Problem Solving forum
“As an aside, let''s look at another way to solve the second question (and similar ones): When you have two individual group averages and an overall average, you can find the weights of the group using a simple formula, illustrated by plotting the information on a number line: ...”
May 13, 2011
Stuart Kovinsky posted a reply to Weighted Average Problem in the Problem Solving forum
“As illustrated by the problems you posted, it depends on what information you''re given and for what information you''re solving. First, you don''t have to assume that there are exactly 200 and 100; you can use any numbers that follow the rule given: Jar A contains twice as many red ...”
May 13, 2011
Stuart Kovinsky posted a reply to integers----> nice question in the Problem Solving forum
“Hi, if R is a set of all integers between two specific integers, inclusive, then by definition R will be a set of consecutive integers. For example, if a=2 and c=10, then R = {2, 3, 4, 5, 6, 7, 8, 9, 10}.”
May 11, 2011
Stuart Kovinsky posted a reply to If m is an integer in the Data Sufficiency forum
“Hi, we''re not told that m is not divisible by 2; we''re told that m/2 is not an EVEN integer. So, for example, if m=6, then m/2 = 6/2 = 3, which is not an even integer. Is 6 odd? NO. However, if m=5, then m/2 = 5/2 = 2.5, which is not an even integer. Is 5 odd? YES. Since both even ...”
May 10, 2011
Stuart Kovinsky posted a reply to GMATPrep Problem in the Problem Solving forum
“As a follow-up to Mitch''s post (backsolving is a great way to solve this question), we can use common sense and a bit of arithmetic to quickly eliminate two of the five choices, making backsolving even more viable. We know that the correct answer is the product of x and (x-1). Since this is the ...”
May 10, 2011
Stuart Kovinsky posted a reply to integers----> nice question in the Problem Solving forum
“Hi! 4, 5, 7 and 10 are not consecutive numbers, so the rule doesn''t apply. "Consecutive" means that the numbers are a fixed distance apart. Some examples of sets of consecutive numbers to which the rule applies: {1, 2, 3, 4} {3, 6, 9, 12} {-10, -5, 0, 5, 10} {11, 14, 17, 20} ...”
May 10, 2011
Stuart Kovinsky posted a reply to GMAT PREP NEGATIVE CUBE ROOT PROBLEM in the Problem Solving forum
“Hi, almost certainly the easiest way to solve this problem is via brute force. -1^3 = -3 -2^3 = -8 -3^3 = -27 -4^3 = -64 -5^3 = -125 So, the cube root of -89 is between -4 and -5.”
May 10, 2011
Stuart Kovinsky posted a reply to manhattan gmat sentence correction who v.s whom in the Sentence Correction forum
“Hi! Not at all - we''d say "one of them is blind", not "one of they is blind"; since you''d use "them" over "they", you know to use "whom" over "who".”
May 10, 2011
Stuart Kovinsky posted a reply to Type of CR question - PR CAT in the Critical Reasoning forum
“Hi, (D) might make us doubt that the conclusion is wrong, but it doesn''t help us decide if the study is accurate; only information related to the study could possibly do so.”
May 10, 2011
Stuart Kovinsky posted a reply to Type of CR question - PR CAT in the Critical Reasoning forum
“Hi! The question asks us to determine the accuracy of the study. Accordingly, the correct answer must be a fact that''s directly related to the study itself, not the results. This distinction is very important; we''re not being asked to strengthen or weaken the study''s conclusion - we''re ...”
May 9, 2011
Stuart Kovinsky posted a reply to At present the Hollywood Restaurant has only standard-height in the Critical Reasoning forum
“Correct - the argument is focused on the impact of the tables on the celebrity watchers, not the celebrities.”
May 9, 2011
Stuart Kovinsky posted a reply to Absolutely Value Inequality in the Problem Solving forum
“Hi! I''ve bolded the key words in the question to emphasize what we''re really being asked. While you''re correct that the inequality in (B) includes all of the points in the shaded part of the number line, it''s also true that (B) includes some points that aren''t in the shaded region, e.g. ...”
May 9, 2011
Stuart Kovinsky posted a reply to What is the value of Y in the Data Sufficiency forum
“Just a quick point on solving absolute values, although it didn''t turn out to make a difference to this particular question. Remember, the absolute value of anything is non-negative; "non-negative" is NOT the same thing as positive. So, if we solve a bit more precisely: 3*abs ...”
May 9, 2011
Stuart Kovinsky posted a reply to tricky odds and evens problem in the Data Sufficiency forum
“Hi! I really doubt that I''d even attempt to tackle a question like this algebraically, since the math is a bit on the nutty side. The tougher the questions get, the more you need to use alternative approaches if you want to beat the clock. In all likelihood, I''d pick numbers until I saw a ...”
May 9, 2011
Stuart Kovinsky posted a reply to Several years ago the diet industry in the Sentence Correction forum
“Here''s the important thing to remember about pronoun ambiguity: it''s a style issue, not a grammar issue. So, if you have to choose between two choices, both of which are grammatically correct but one of which is ambiguous, go with the non-ambiguous choice. However, when all the choices ...”
May 9, 2011
Stuart Kovinsky posted a reply to OG 12 Q 33 in the Critical Reasoning forum
“Hi, anytime a question asks you to draw a conclusion based on the statements in the stimulus, it''s an inference question. Since this question asks us what "must be true on the basis of the statements... above", it falls clearly into that category.”
May 9, 2011
Stuart Kovinsky posted a reply to At present the Hollywood Restaurant has only standard-height in the Critical Reasoning forum
“Hi! "vulnerable to criticism" in the stem indicates that we have a logical flaw question. Flaw questions are fairly rare on the GMAT, but they do show up occasionally. However, since flaw questions are very closely related to weakening questions, the most common CR question type, ...”
May 9, 2011
Stuart Kovinsky posted a reply to Word problem (book answer looks dubious) in the Data Sufficiency forum
“Hi, we can quickly determine that (2) is insufficient alone, since we''re not told that he sold the bracelet for the original asking price; we certainly can''t assume such to be the case. For all we know he had to discount the bracelet 12 times before he eventually sold it. Since we don''t ...”
May 9, 2011
Stuart Kovinsky posted a reply to tricky odds and evens problem in the Data Sufficiency forum
“Hi, you''re 100% correct that on the GMAT the two statements will never conflict; however, there''s no conflict on this particular question. (1) tells us that z is 2/3 of an even integer; (2) tells us that z is 2/5 of an even integer; however, nowhere does it say that z is 2/3 and 2/5 of the ...”
May 9, 2011
Stuart Kovinsky posted a reply to GMAT TestPrep Question in the Data Sufficiency forum
“Hi! manpsingh''s approach is good, and perhaps easier to understand if we look at the information slightly differently. First, let''s think about the question stem (always a good first step in DS). We see that we have a perfect square on top and a perfect square on the bottom; however, ...”
May 9, 2011
Stuart Kovinsky posted a reply to Divisibility problems in the Data Sufficiency forum
“Hi! You can certainly solve this type of problem by applying divisibility rules, but like almost all data sufficiency yes-no number property problems, picking numbers is also an excellent approach. When you pick numbers in data sufficiency, it''s vital to follow 2 steps: 1) pick a number ...”
May 9, 2011
Stuart Kovinsky posted a reply to Number Properties in the Problem Solving forum
“Hi! The question is correct. Both of you assumed that x has to be an integer, something not stipulated by the question. Since x doesn''t have to be an integer, one cannot assume that if 9 is a factor of 2x, 9 must also be a factor of x. For example, if you plug in x=4.5, you get: 9 is ...”
May 9, 2011
Stuart Kovinsky posted a reply to # of 5 digit numbers in the Problem Solving forum
“Hi! The search bar is a very valuable tool on Beat the GMAT, since many of the same questions get posted in different threads. For example, I did a search on "how many five-digit numbers" and got 4 pages of responses. Here are some links to other threads discussing this question: ...”
May 9, 2011
Stuart Kovinsky posted a reply to GMAT STATISTICS in the Problem Solving forum
“Hi, when looking at statistical data, it is, not surprisingly, all about the numbers. Consequently, regardless of whether you''re talking about people or animals or money, you still just view each data point as a number in a set. Accordingly, there''s really no such thing as the ...”
May 5, 2011
Stuart Kovinsky posted a reply to sequence in the Problem Solving forum
“Hi, since the first term is 1, and since we double to find the next term, we can quickly see that the nth term of the sequence is simply 2^(n-1). In other words: term1 = 2^0 term2 = 2^1 term3 = 2^2 and so on. So, the 16th, 17th and 18th terms will be: 2^15, 2^16 and 2^17. Next, ...”
May 5, 2011
Stuart Kovinsky posted a reply to Aristotle SC in the Sentence Correction forum
“Hi, (D) commits the unforgivable error of changing the meaning of the sentence; since the original is written in the present tense, we shouldn''t change to the past unless that was clearly the author''s intention. The problem with (A) is lack of parallelism; "is roasting... while he ...”
April 29, 2011
Stuart Kovinsky posted a reply to 1000 DS section 17 question 20 in the Data Sufficiency forum
“Hi Prashant, are you sure that you''ve posted (1) correctly? In its current form, (1) is definitely sufficient. Algebraically: 5^(k-1)> 3000 multiplying both sides by 5: 5^(k-1) * 5^1 > 15000 5^(k-1+1) > 15000 5^k > 15000 and if 5^k is more than 15000, it''s ...”
April 29, 2011
Stuart Kovinsky posted a reply to Probability quest-Princeton Review in the Problem Solving forum
“For combinations vs permutations, the important question to ask is "does order matter". If order doesn''t matter, use combinations; if order does matter, use permutations. Here''s another way you can think about it: After I''m done selecting the subgroup, am I going to do anything ...”
April 29, 2011
Stuart Kovinsky posted a reply to least value venn diagram in the Problem Solving forum
“Hi Nitin, here''s a good general rule for GMAT mini/maxi questions: whenever you''re asked to minimize or maximize one part of a problem, do so by maximizing or minimizing other parts of the problem. Here''s a simpler example: We think: we want to maximize the number of cars with AC, so ...”
April 29, 2011
Stuart Kovinsky posted a reply to One more intrestg one - its a common 1 but nice 1 in the Sentence Correction forum
“whats the difference when we say sloth sleep 15 hours a day and when we say the sloth sleeps 15 hours a day . Are both sentences acceptable when we are talking about the sloth/sloths in general ?[/quote] Both are acceptable, as long as they agree with and make sense in the context of the other ...”
April 29, 2011
Stuart Kovinsky posted a reply to Aristotle RC <700 level> in the Sentence Correction forum
“I''m really not in love with any of the choices (what''s the source? I''ve never heard of Aristotle - well, at least the Aristotle I have heard of lived a couple of millenia pre-GMAT), but B is the clear winner of the available options. Let''s look at C again: (C) compares 2009 to the ...”
April 29, 2011
Stuart Kovinsky posted a reply to Brutal SC #54 in the Sentence Correction forum
“Hi! Old question, but still worth a look. "it" doesn''t refer to anything sensical in this sentence. Let''s construct a similar, but simpler, example to illustrate. vs Does "they" make sense in this statement? No, because we''re comparing two facts about the ...”
April 29, 2011
Stuart Kovinsky posted a reply to One more intrestg one - its a common 1 but nice 1 in the Sentence Correction forum
“Hi! A great way to quickly solve sentence correction problems is to scan the choices for differences and eliminate the versions that you don''t like. Here, we see that we have a 3-2 split to begin the choices; A, B and C begin with "sloths" and D and E begin with "the ...”
April 29, 2011
Stuart Kovinsky posted a reply to Probability quest-Princeton Review in the Problem Solving forum
“Hi Ankit, the 9 items are different, it''s just that some of them are the same colour; there are 9 physical jars from amongst which to choose, so 9 is the total number of objects. The only time (at least on the GMAT) that we worry about objects being distinct is for permutations - i.e. we''re ...”
April 29, 2011
Stuart Kovinsky posted a reply to Probability and combinations in the Problem Solving forum
“Hi, on most complicated probability problems on the GMAT, the "one minus" approach is the quickest way to solve. This approach is based on the equation: Prob(what you want) + Prob(what you don''t want) = 1 which rearranges to: Prob(what you want) = 1 - Prob(what you don''t ...”
April 29, 2011
Stuart Kovinsky posted a reply to Mixture with Alligation in the Problem Solving forum
“Hi! I''ve never heard of the "alligation" method - does it involve feeding part of the mixture to alligators? Sounds dangerous! As an aside, this question is seriously flawed and impossible to answer in its current form, since you can''t answer a "how much" question unless ...”
April 29, 2011
Stuart Kovinsky posted a reply to any simpler way.. in the Problem Solving forum
“While this question would never appear on the GMAT ("at least twice greater than" makes no sense - clearly the author meant to say "at least twice as much as"), it illustrates an interesting strategic approach. Let''s start with a fundamental rule of the exam: there can only ...”
April 28, 2011
Stuart Kovinsky posted a reply to Set of 3 in the Problem Solving forum
“You know that it''s going to be a horribly worded question as soon as you see the word "curriculums" in the first sentence (and "participate in some curriculums" is also non-idiomatic, even if "curriculums" was a word). If you find non-official questions written in ...”
April 28, 2011
Stuart Kovinsky posted a reply to 1 more Mixture problem in the Problem Solving forum
“Given that "shift-5" = %, I''m pretty sure that it should be 25%, not 255. Change 255 to 25% and the question makes sense.”
April 28, 2011
Stuart Kovinsky posted a reply to Aristotle Q53 in the Sentence Correction forum
“Hi, I highly doubt that you''d ever see these two choices on the GMAT - there''s a small stylistic difference, but both are essentially equal in terms of "goodness". I would consider whether "is" is the grammatically correct verb for the last part of the sentence; since ...”
April 28, 2011
Stuart Kovinsky posted a reply to Artificial reefs in the Critical Reasoning forum
“Hi! Any chance you can repost the question with the original language? The current version has so many grammatical errors that it actually hurts my head to read it! Leaving out articles (e.g. "a", "the", "an"...) and using improper tenses (e.g. "sea life ...”
April 27, 2011
Stuart Kovinsky posted a reply to gmat CR...explanations please in the Critical Reasoning forum
“Hi, the source is bad - (B) is definitely the correct choice, as explained in the many posts above!”
April 27, 2011
Stuart Kovinsky posted a reply to permutations and combinations in the GMAT Math forum
“Hi! First, we need to know a trick for mutliples of 3: the sum of the digits of any multiple of 3 will also be a multiple of 3. So, for example, 54321 is a multiple of 3, since 5+4+3+2+1=15 and 15 is a multiple of 3. Now we need to see which combinations of those 5 digits will sum to a ...”
April 27, 2011
Stuart Kovinsky posted a reply to average in the Data Sufficiency forum
“Hi! We see we''re being tested on averages, so let''s start by jotting down the average formula: average = (sum of terms)/(# of terms) We know that the average is x and that the income of one person increases by 25%. We don''t know the number of people in the group or the sum of their ...”
April 26, 2011
Stuart Kovinsky posted a reply to ps:pnc in the Problem Solving forum
“Not a real GMAT question (on the GMAT, "palindrome" would be defined, there would be more specificity regarding repeating numbers and, of course, there would be answer choices), but an interesting counting question nonetheless. Ignoring the actual numbers, let''s use X, Y and Z to ...”
April 26, 2011
Stuart Kovinsky posted a reply to A set consists of of several different integers. Is the pr.. in the Data Sufficiency forum
“Hi, the order in which you write out the set is irrelevant to sufficiency for this question. Using your examples, whether you write the first set as: {2, 5, 8, 20} or {8, 20, 2, 5} the product of the greatest and smallest terms is still 20*2 = 40 since "greatest" ...”
April 26, 2011
Stuart Kovinsky posted a reply to Clarification for Square Roots in the Problem Solving forum
“Correct (if by square sign you mean anything raised to the power of two, like in your original example)!”
April 25, 2011
Stuart Kovinsky posted a reply to Clarification for Square Roots in the Problem Solving forum
“Hi, you answered your own question early on, when you said: By mathematical convention, the "√x" should be read as "the non-negative root of x" (so √0 = 0, but in all other cases √x is the positive root of x). Like all math rules, this applies regardless of how ...”
April 25, 2011
Stuart Kovinsky posted a reply to We who in the Sentence Correction forum
“Hi! "then" doesn''t change the meaning of the sentence, it''s just grammatically incorrect. "We who then graduated ... in the 1960s..." implies that an action took play before the "then", but there''s no such action in the sentence. For example, if a sentence ...”
April 24, 2011
Stuart Kovinsky posted a reply to Stuart Kovinsky --- did i get your solution wrong?? in the Data Sufficiency forum
“Hi, as Ian notes, if you have a question about a post in an existing thread, it''s much more efficient to just reply to that thread rather than start a new one. In any case, Ian answers your specific question in the thread he linked (thread hijacker!) and I believe his answer is the same as on ...”
April 24, 2011
Stuart Kovinsky posted a reply to 6 married couples in the Problem Solving forum
“Hi! Whenever you make multiple simultaneous selections, you can treat the question as though you''re selecting the items one at a time; let''s do that on this question. Our first person can be anyone, so there''s a 12/12 chance that the person is "safe". Once we choose our first ...”
April 24, 2011
Stuart Kovinsky posted a reply to Cost to edge a flower garden in the Problem Solving forum
“Hi! Vivian''s advice is dead on; the old adage "you get what you pay for" definitely applies to most free GMAT questions available on the web. Probably the biggest advantage of going with "brand name" materials is that you know that the top prep companies didn''t get to where ...”
April 23, 2011
Stuart Kovinsky posted a reply to Product of consequtive integers problem in the Problem Solving forum
“Hi! Our number has to be a multiple of 990. The only way it could possibly be multiple of 990 is if it contains all of the prime factors of 990. Another way to phrase the question is: if n!/990 is an integer, what''s the smallest possible value of n? So, 990 must divide into n!, which ...”
April 23, 2011
Stuart Kovinsky posted a reply to Cost to edge a flower garden in the Problem Solving forum
“Hi! The question definitely isn''t worded clearly, since the common interpretation would be surrounding the flower bed with stones; however, by reverse engineering the choices it''s clear that''s not the case. So, ignoring "filling in the corners" but using the rest of your ...”
April 23, 2011
Stuart Kovinsky posted a reply to Co-ordinate question from BTG practice questions in the Data Sufficiency forum
“Hi! (1) is insufficient, because it doesn''t tell us anything else about the line. It could simply be the line y=2, in which case it wouldn''t pass through quadrant III, or it could be any line with a positive slope, in which case it would pass through the quadrant. (2) tells us that the line ...”
April 23, 2011
Stuart Kovinsky posted a reply to Selection Problem in the Problem Solving forum
“Hi! This question has been discussed many times - I ran a search on "4 people have exactly 1 sibling" and hit a ton of threads. Here''s one in which I explain the question: [url]http://www.beatthegmat.com/sibling-probability-t46183.html[/url] and there are many others if you ...”
April 22, 2011
Stuart Kovinsky posted a reply to museum in the Critical Reasoning forum
“Hi, some always means "at least one" - we can''t quantify any more than that. Since some means "at least one", when we deny (i.e. take the opposite of) some we get "not at least one", which translates as "none". In this particular question, that ...”
April 22, 2011
Stuart Kovinsky posted a reply to A set consists of of several different integers. Is the pr.. in the Data Sufficiency forum
“Hi! It doesn''t matter if the list is in order. "Greatest" means the biggest number in the list and "smallest" means the smallest number in the list, regardless of how you arrange the terms. For example, in the sets: {1, 2, 3, 4, 92} and {2, 4, 92, 3, 1} the ...”
April 22, 2011
Stuart Kovinsky posted a reply to a data from gmatclub in the Data Sufficiency forum
“Hi! It''s key to understand exactly what a statement is telling you. (1) x^2 - 2*x + A is positive for all x To satisfy this statement, we have to have an A that makes the expression positive for EVERY POSSIBLE value of x. Well, if x=0, then the expression simply equals A. So, in order ...”
April 22, 2011
Stuart Kovinsky posted a reply to according vs in accordance : such as vs such X as in the Sentence Correction forum
“Doh! Now I''m jonesing for coffee and need to make a pot!”
April 22, 2011
Stuart Kovinsky posted a reply to Stuart Kovinsky ---- Could you please explain this in the Problem Solving forum
“Hi, first, here''s the original question: Second, I think (I didn''t write the explanation that you posted, so I can''t be sure!) that the person who wrote that explanation was trying to decide on the proper interpretation of the question. Does "if both B and C had 1/4 of what A ...”
April 22, 2011
Stuart Kovinsky posted a reply to museum in the Critical Reasoning forum
“A tool you can use for assumption questions is the Denial Test. The correct answer to an assumption question is something that must be true for the argument to hold; an essential building block of the argument. The opposite of the correct answer will show that the argument is wrong; it will ...”
April 22, 2011
Stuart Kovinsky posted a reply to according vs in accordance : such as vs such X as in the Sentence Correction forum
“Hey Mitch, great breakdown of the "according to" "in accordance with" angle, but I''m not sure that I agree with this last point. Is it not grammatically correct to say: If we look at the sentence in this question, we have the same format: I don''t see a problem ...”
April 22, 2011
Stuart Kovinsky posted a reply to properties of a work of art in the Critical Reasoning forum
“Hi! First thing to note about this question - it''s a retired question from an old LSAT exam. Further, although assumption questions do appear on the GMAT, it would be very rare for them to be this complex. However, we can still treat this as we would a simpler assumption question: identify ...”
April 20, 2011
Stuart Kovinsky posted a reply to Expert way to eliminate the wrong choices. in the Sentence Correction forum
“Hi! When we have an "or" list, each item needs to be able to stand alone in the sentence. "Slowing the growth forests" makes no sense - we definitely need an "of" between "growth" and "forests". Accordingly, we can eliminate (A). (B) lacks ...”
April 20, 2011
Stuart Kovinsky posted a reply to ps - square in square in the Problem Solving forum
“Mitch has provided a great example of picking numbers, so let''s try something different: applying basic principles and avoiding math. First, we need to understand the question: we have a smaller equilateral triangle inside a larger one and the triangles are similar - in other words, the ...”
April 20, 2011
Stuart Kovinsky posted a reply to og 82 in the Problem Solving forum
“Picking numbers is a great approach and, using a bit of common sense, you should realize that you only have to try two numbers. First, we recognize that if n is a multiple of 3 then every choice will also be a multiple of 3. Second, since "3" is the important number, we recognize ...”
April 20, 2011
Stuart Kovinsky posted a reply to Please can some one solve this probabilty question for me? in the Problem Solving forum
“Hi, as others have noted, this is not even remotely similar to a GMAT question. While it''s an interesting statistics problem, people studying for the GMAT can safely ignore it.”
April 20, 2011
April 20, 2011
Stuart Kovinsky posted a reply to ds:numbers in the Data Sufficiency forum
“A good test of our ability to avoid complex calculations! (1) the range given only contains one multiple of 5 (1240), so (1) is certainly sufficient: eliminate (B), (C) and (E). (2) we could divide all 3 parts by 3, but we''d really rather avoid the math. There are three ways we can deal ...”
April 19, 2011
Stuart Kovinsky posted a reply to ps:pnc in the Problem Solving forum
“Hi again! When we''re selecting a subgroup out of a larger group, think combinations. As always, let''s start by jotting down the combinations formula: nCk = n!/k!(n-k)! in which n is the total number of objects and k is the number in our subgroup. In this question, we''re making two ...”
April 19, 2011
Stuart Kovinsky posted a reply to ps:probability in the Problem Solving forum
“Please post the exact wording of the original question along with the source. On this particular question we can determine what''s being asked, but grammatical errors (of which there are a few in this post) can alter the meaning of a question. Also, please post the answers, since many GMAT ...”
April 19, 2011
Stuart Kovinsky posted a reply to although certain great apes in the Sentence Correction forum
“"consider" is often tested on the GMAT because it''s one of the rare verbs that''s generally not followed by a preposition. For example, a correct sentence is: However, many people are tempted to say: or both of which are idiomatically incorrect. However, as with ...”
April 19, 2011
Stuart Kovinsky posted a reply to MGMAT CAT 6 in the Data Sufficiency forum
“Hi! Some tricky working in (1) which we need to carefully translate, but once we do it''s clear that each statement is sufficient alone. Q: What''s the probability that Memphis isn''t chosen to host? First, we need to recognize that if we can answer "what''s the probability that ...”
April 19, 2011
Stuart Kovinsky posted a reply to PS - divisor>1 Q in the Problem Solving forum
“Hi! I''d write out all of the perfect squares less than 75 (since that''s the biggest answer): 4, 9, 16, 25, 36, 49, 64 and then simply look for the choice for which none of those are a factor.”
April 19, 2011
Stuart Kovinsky posted a reply to a/b > b/c - inequality in the Problem Solving forum
“Hi, you have to be very careful when manipulating inequalities that involve variables. Remember, when you multiply or divide both sides by a negative, you have to swap the inequality. Since we don''t know the signs of b or c, it''s NOT safe to cross multiply. Let''s pick numbers to ...”
April 19, 2011
Stuart Kovinsky posted a reply to MGMAT qurestion a tough one..pls advice a nice approach in the Problem Solving forum
“Hi! Since length is related to the number of prime factors, and since we want to maximize the length, we want to use the smallest primes possible. So, let''s make all the primes involved 2. So, x and y will both be powers of 2. Let''s let: x = 2^a and y = 2^b so that our ...”
April 19, 2011
Stuart Kovinsky posted a reply to Looking Too Deep? in the Data Sufficiency forum
“Hi! What''s the source of this question? I ask because there''s important wording missing from the statements in order for (B) to be the correct answer. You''re 100% right in your counter-argument to (2) being sufficient. For (2) to be sufficient alone, it should read: Both statements ...”
April 18, 2011
Stuart Kovinsky posted a reply to Probability:-) in the Problem Solving forum
“Hi! Check out: [url]http://www.beatthegmat.com/try-this-one-on-for-size-courtesy-of-manhattan-gmat-t51512.html?cityevent=Chicago-40-706[/url]”
April 18, 2011
Stuart Kovinsky posted a reply to Combinotrics:-) in the Problem Solving forum
“Hi! To solve this, let''s start with the easier embedded question: In how many ways can 6 people be arranged in a line? When we''re arranging n distinct objects, there are n! possible arrangements. So, there are 6! = 6*5*4*3*2 = 720 total arrangements. (Another way to solve: for the ...”
April 18, 2011
Stuart Kovinsky posted a reply to A new strategy for releasing the seals in the Sentence Correction forum
“Hi, what''s the specific source? If you provide the details, I''ll get the question edited. We can definitely introduce new words into the correct answer. Here''s the rule to follow: So, if the new word clears up ambiguity but doesn''t change the meaning of the sentence, then it ...”
April 18, 2011
Stuart Kovinsky posted a reply to fruit seller loses in the Problem Solving forum
“First, there are lots and lots of people who would have no idea what "loses the selling price of 4 oranges" means - especially people for whom English isn''t their first language. So, even though I always understood what you meant, that''s not the point. The point is that if you''re ...”
April 18, 2011
Stuart Kovinsky posted a reply to fruit seller loses in the Problem Solving forum
“I must have a masochistic streak in me - I really don''t know why I keep replying to these threads! This question isn''t written in proper English. What does "loses the selling price of 4 oranges" mean? What does "loss percent" mean? That language is way too ambiguous for ...”
April 18, 2011
Stuart Kovinsky posted a reply to units sold after the reduction in the Problem Solving forum
“Hi, I think there''s a mistake in the question, since the stem clearly states that there''s a 28% increase in sales (a term which usually refers to the number of units sold). Did you mean to say that there''s a 28% increase in gross revenue? Alternatively, if that part of the question is ...”
April 18, 2011
Stuart Kovinsky posted a reply to A new strategy for releasing the seals in the Sentence Correction forum
“Hi, in the context of this sentence, it must be referring to a seal, as in "one of the seals". So, if the choice had read "...track one after the seals..." it would have been slightly better, but still more ambiguous than (E).”
April 18, 2011
Stuart Kovinsky posted a reply to A new strategy for releasing the seals in the Sentence Correction forum
“Hi! I really hope that you copied the question incorrectly, since the non-underlined part is incorrect; it should read "A new strategy for releasing seals..." (the definite article "the" makes no sense in this sentence). If you''ve copied it verbatim, please let me know the ...”
April 18, 2011
Stuart Kovinsky posted a reply to Labor Department’s employment report in the Sentence Correction forum
“This question is a great illustration of the power of scan and eliminate, the essence of the Kaplan Method for Sentence Correction. After reading the sentence once, if nothing jumps out at you, scan the choices looking for differences. The easiest place to spot a difference is right at the ...”
April 18, 2011
Stuart Kovinsky posted a reply to Inuits of the Bering Sea were in the Sentence Correction forum
“Hi! it would be idiomatically acceptable to say "They were in isolation." It would also be acceptable to say "They were isolated from contact with X." However, it''s not acceptable to say "There were in isolation from contact with X." Since (A) and (C) both have ...”
April 18, 2011
Stuart Kovinsky posted a reply to although certain great apes in the Sentence Correction forum
“Hi, two independent clauses must be connected by one and only one connector. In (B), "Although" serves precisely that function. So, unless you''ve mistyped one of the other responses, (B) must be the correct answer. (A) is passive; "it" has no proper antecedent. (C) ...”
April 18, 2011
Stuart Kovinsky posted a reply to Does 'constant' also mean integer? in the GMAT Math forum
“Hi, "constant" is simply the opposite of "variable"; since the GMAT only deals with the set of real numbers, for GMAT purposes a constant is any fixed real number (an integer, fraction, positive, negative, 0, irrational number like pi, etc...).”
April 18, 2011
Stuart Kovinsky posted a reply to Chance of Rain in the Problem Solving forum
“For a discussion of coin flip and pseudo-coin flip questions (the question on this thread is one of the latter), check out: [url]http://www.beatthegmat.com/coin-flip-questions-made-easy-t17911.html#75414[/url]”
April 18, 2011
Stuart Kovinsky posted a reply to standard deviation in the Problem Solving forum
“Hi! I have some bad news for you and some good news. The bad news is that your calculation of SD is way off; the SD of {5, 10, 15} is NOT 5. The good news is that you don''t actually need to know how to calculate SD for the GMAT; you merely have to have a basic idea of what SD is and when ...”
April 18, 2011
Stuart Kovinsky posted a reply to Weird Question in the Problem Solving forum
April 17, 2011
Stuart Kovinsky posted a reply to Three Overlapping Sets Formula in the Problem Solving forum
“Edit: Posted, but might have changed my mind - need to think about it some more!”
April 17, 2011
Stuart Kovinsky posted a reply to y > 0 in the Problem Solving forum
“The question could definitely be worded more clearly (I''m not sure of the source, but it sounds "homemade"). Let''s assume, for the sake of the question, that it reads "MUST BE positive EXCEPT" instead of "IS positive EXCEPT". Even with that change, (D) and (E) both ...”
April 15, 2011
Stuart Kovinsky posted a reply to benchmarking values - fraction in the Problem Solving forum
“Hi! First, I wholeheartedly agree with Brent - please provide the answer choices for every question that you post, since many strategic approaches rely on the choices. Dealing with your specific question, however: Since we''re rounding 10/22 UP to 1/2, I''d round 5/18 DOWN to 1/4 - that ...”
April 15, 2011
Stuart Kovinsky posted a reply to Divisibility - Number Theory in the Problem Solving forum
“Hi! This question has been discussed a number of times. Here''s one thread: [url]http://www.beatthegmat.com/integers-mgmat-t13639.html[/url] Enjoy!”
April 15, 2011
Stuart Kovinsky posted a reply to OG 11 DS #132 in the Data Sufficiency forum
“Hi, first off, it''s important to understand exactly what (2) says - I''ve seen many people get this question wrong because they misinterpret (2). This means that if you take any two distinct factors of n, you''ll get an odd difference. How is this possible? Only in 1 case: n must have ...”
April 14, 2011
Stuart Kovinsky posted a reply to GMATPrep Quetsion in the Data Sufficiency forum
“Sure! Let''s start by breaking down the question stem. We know that 72% of males and 80% of females have applied to college. We want to know that percent of the entire class is male. We think: lots of missing information; since the question is asking us for a percent, not an actual number, ...”
April 14, 2011
Stuart Kovinsky posted a reply to GMATPrep Quetsion in the Data Sufficiency forum
“Hi, in it''s current form, (2) is not sufficient. However, if (2) were to read: then we could use weighted averages (or ratios) to figure out what percent of the senior class is male. Are you sure that you reproduced the question correctly? What''s the source?”
April 14, 2011
Stuart Kovinsky posted a reply to O.G Quant Review in the Problem Solving forum
“The only information we have about x and y is that they''re positive integers, so there will be very few conclusions we can draw about their greatest common factor. However, here''s one thing we do know: the greatest common factor of any positive integer is the integer itself. Accordingly, ...”
April 13, 2011
shovan85 started following Stacey Koprince
April 13, 2011
shovan85 started following lunarpower
April 13, 2011
Stuart Kovinsky posted a reply to [CR][PnR] HSPA posts in the Data Sufficiency forum
“We see a yes/no inequality question with variables. We think: be careful about multiplying or dividing both sides by a variable - if the variable could be negative, weird things may happen! (1) we immediately consider p=r=0. In this case, 1/p is undefined, so it''s impossible to answer the ...”
April 13, 2011
Stuart Kovinsky posted a reply to Is xy + xz = 0 in the Data Sufficiency forum
“The question becomes much simpler if you simplify the question! Is xy + xz = 0? Is x(y + z) = 0? When will this be true? If x=0 or (y + z) = 0. (1) x = 0... sufficient! (2) y + z = 0... sufficient! Each statement is sufficient alone - choose (D).”
April 13, 2011
Stuart Kovinsky posted a reply to Functions junctions mess! in the Problem Solving forum
“Hi! You made a couple of errors. First, the first term is 1/g(2), not g(2). So, subbing in: 1/g(2) = 1/(6/1) = 1/6 and the second term is: 1/g(x) = 1/((x^2 + 2) / (x - 1)) = (x-1)/(x^2 + 2) Taking the product of those two terms: (1/6)*(x-1)/(x^2 + 2) = (1)(x-1)/(6)(x^2 + 2) ...”
April 13, 2011
Stuart Kovinsky posted a reply to Geometry - Circles and Squares. in the Data Sufficiency forum
“For DS, the instructions Do say that diagrams are not drawn to scale. From the Official Guide (p24 of 12th ed.): Based on the first point, we know that DS diagrams are not necessarily drawn to scale and we can''t rely on the way that they appear. Based on the third point, we know that ...”
April 12, 2011
Stuart Kovinsky posted a reply to MGMAT CAT 4 in the Data Sufficiency forum
“I''m really not sure where you came up with that pattern, but it definitely doesn''t match what will happen on this question. If you take ANY 7 numbers ending in 3 and multiply them together, the units digit of the full product will be the same as the units digit of 3^7. Now, powers of 3 ...”
April 12, 2011
Stuart Kovinsky posted a reply to More Primes in the Problem Solving forum
“As noted in my post above, you multiply the value of each chip by the values of all of the other chips. So, if you have 1 blue chip, the total value of the blues is: 1^1 = 1. Similarly, if you have 10 blue chips, the total value of the blues is: 1^10 = 1 not 1*10 = 10 which is ...”
April 12, 2011
Stuart Kovinsky posted a reply to More Primes in the Problem Solving forum
“You''re misinterpreting the statement to read "the sum of the purple chips is greater than that of the green chips, but less than that of the red chips"; it''s not the sums that are being compared, but the values of the individual chips. As we can see from the question: ...”
April 12, 2011
Stuart Kovinsky posted a reply to MGMAT CAT 4 in the Data Sufficiency forum
“Interesting question! As always, one key to success is to understand exactly what the question is asking. Here, we only care about the units (i.e. ones) digit of n; accordingly, we only care about the units digit of (243^x)*(463^y). Since both terms end in "3", we''re multiplying ...”
April 12, 2011
Stuart Kovinsky posted a reply to MGmAT CAT 4 in the Problem Solving forum
“Hi, we can''t prove (I) is false, but that''s not what we need to do to disqualify it - we merely need to show that it COULD be false. We can certainly pick numbers to show that (I) need not be true, let''s just change the days that I used for my counter example to (III): A''s regular wage ...”
April 12, 2011
Stuart Kovinsky posted a reply to MGMAT CAT - Root of a Square in the Problem Solving forum
“Based on the question, we know there are at least two values for x. If there were only 1 possible value, the GMAT wouldn''t use the word "could". We also see squares and roots, alerting us to a positive and negative solution. Now, let''s put on our GMAT question writer hats ...”
April 12, 2011
Stuart Kovinsky posted a reply to MGMAT CAT - ratio'S prob in the Problem Solving forum
“We''ve seen a good algebraic solution, so let''s attack the question strategically, by backsolving. When the answer choices are numbers and the question is simple (e.g. "how many red marbles could there be?"), then backsolving is often a very effective approach. If you can''t quickly ...”
April 12, 2011
Stuart Kovinsky posted a reply to MGmAT CAT 4 in the Problem Solving forum
“Let''s think things through logically: 1) we know that they worked the same number of hours during the week; 2) we know they earned the same total salary for the week; 3) we know that Alan''s regular wage is higher; and 4) we know that Barney gets paid double time on Saturdays. If they only ...”
April 12, 2011
Stuart Kovinsky posted a reply to Permutations in the Problem Solving forum
“Hi! This isn''t actually a permutations question, since order doesn''t matter. It can be solved with either combinations or probability. Here''s another thread discussing the question: [url]http://www.beatthegmat.com/i-suck-at-probability-need-desperate-help-t8927.html[/url]”
April 12, 2011
shovan85 posted a reply to Permutations in the Problem Solving forum
“Need to form a group of 12 people. This can be done in C(15,12) = 455 2/3 of the 15 are Men = 10 men 1/3 of the 15 are women = 5 women in the formed group 2/3 at least are needed to be men, so at least 8 men needed. C(10,8) * C(5,4) + C(10,9) * C(5,3) + C(10,10) * C(5,2) = 225 + 100 + ...”
April 12, 2011
Stuart Kovinsky posted a reply to Distinct members and committee in the Problem Solving forum
“While I admire your ambition, I''m a bit confused about your motives. Are you studying for the GMAT? If so, why not work on the questions that are actually out there rather than trying to create some of your own, especially since you''re just getting started? A big part of GMAT success is ...”
April 11, 2011
Stuart Kovinsky posted a reply to GMAT Club PS question 2 in the Problem Solving forum
“Hi, if t=u=0, then (C) would be true and (A) would be false, so there''s at least some difference between the options. However, if two answer choices were exactly the same, and you noticed that fact, then you could quickly eliminate both choices (unless it''s a roman numeral question); since ...”
April 11, 2011
Stuart Kovinsky posted a reply to Percents and increasing Speed in the Problem Solving forum
“Hi, it''s very useful to know the basic fraction-decimal-percent conversions by heart, namely: 1/2 = .5 = 50% 1/3 = .333 = 33.3% 1/4 = .25 = 25% 1/5 = .2 = 20% 1/6 = .1667 = 16.67% 1/8 = .125 = 12.5% 1/9 = .111 = 11.1% 1/10 = .1 = 10% 1/20 = .05 = 5% (1/7 = approx .14 = approx 14%) ...”
April 11, 2011
Stuart Kovinsky posted a reply to Distinct members and committee in the Problem Solving forum
“I''m not sure why you''d modify a Kaplan question, only include 4 answer choices (instead of the 5 that appear on the actual GMAT) and leave it open to multiple correct answers, even though the question itself implies that there''s only 1 possible answer. As a result, the way you''ve modified it ...”
April 11, 2011
Stuart Kovinsky posted a reply to data sufficiency problem in the Data Sufficiency forum
“Your mistake is a simple one - you didn''t take into account the condition set in the question stem:”
April 11, 2011
Stuart Kovinsky posted a reply to data sufficiency problem in the Data Sufficiency forum
“Sometimes it helps to think of real world scenarios to help you visualize what''s going on in a question. We know that the top and bottom lines are parallel, but don''t know the relationship between the vertical lines (PQ and SR). Picture a street with houses on both sides. PS is the north ...”
April 11, 2011
Stuart Kovinsky posted a reply to Exponents in the Data Sufficiency forum
“As is the case with a lot of complex DS questions, we can make our lives easier by simplifying the question. We know that p and q are both non-zero integers. So, when will p^(3q) NOT be an integer? Well, if q is positive, then p^(3q) will always be an integer. If q is negative, then p^(3q) ...”
April 11, 2011
Stuart Kovinsky posted a reply to prime-saturated in the Problem Solving forum
“Hi, you''re not expected to be familiar with that term before seeing this question - the question provides the definition. According to the definition, "prime saturated" means that the product of the distinct prime factors must be less than the root. Once we understand the ...”
April 11, 2011
Stuart Kovinsky posted a reply to GMAT PREP QUESTION in the Problem Solving forum
“This question is typical of the most common way the GMAT is currently testing standard deviation. All you need to solve is a very basic understanding of what SD is - the question itself is much simpler than it seems. To solve quickly every time, draw a number line and put the mean in the ...”
April 11, 2011
Stuart Kovinsky posted a reply to Probability Question in the Problem Solving forum
“Hi, when you select multiple items simultaneously, you can treat the question as though you select them one at a time, without replacement. So, our question becomes: If there are 2 red marbles and 3 green marbles in a bag, and you select a marble, then select a second marble without ...”
April 11, 2011
Stuart Kovinsky posted a reply to long equation !! stuck in the GMAT Math forum
“First up, what''s the question? Solve for a possible value of n? Solve for all the values of n? Without the question (and choices), it''s impossible to find the best possible approach. Assuming that we need all the values of n, I''d start with Brett''s analysis: n is common to all 3 terms, ...”
April 10, 2011
Stuart Kovinsky posted a reply to GMAT Prep: Number Properties in the Problem Solving forum
“You could solve for an answer in terms of H, but you couldn''t answer with a definitive number.”
April 5, 2011
Stuart Kovinsky posted a reply to Factor Problem in the Data Sufficiency forum
“Hi Yvonne, Let''s start by simplifying the question: When will xy be divisible by 9? When xy contains all the primes contained by 9. So, rephrasing the question: On to the statements! (1) xy is divisible by 6, or: xy contains at least one "2" and and least one ...”
April 5, 2011
Stuart Kovinsky posted a reply to GMAT Club DS question in the Data Sufficiency forum
“Hi, Mitch''s explanation is spot on (as usual), I just want to focus on the specific mistake you made, since it''s probably the most common way that test takers go wrong in data sufficiency. When you evaluate a statement, you must take its truth for granted. In other words, the only numbers ...”
April 5, 2011
Stuart Kovinsky posted a reply to Problem : Data Sufficiency - 3 in the Data Sufficiency forum
“What about X = {0} and Y = {0}? Now the sum of the means = combined mean, giving us a "no" answer to the questions. Moral of the story: "non negative" means "0 or positive"!”
April 5, 2011
shovan85 posted a reply to Investment funds and pharmaceutical corporations in the Critical Reasoning forum
“(A) Product development is too costly for a single corporation to fund without research and development partnerships. (B) Product development partnerships between pharmaceutical corporations and investment funds are more common now than they were in the recent past. (C) Product development ...”
March 31, 2011
shovan85 started following arora007
March 30, 2011
shovan85 started following beakim
March 30, 2011