Search found 36 matches
To answer my own question, I did find some helpful information in the math review of OG 11. Here is what I learned, hopefully this will help others who are struggling as I was: To find the standard deviation: 1) find the mean of the numbers 2) find the difference between each number and the mean 3) ...
- by allenkt
Mon May 07, 2007 6:40 am- Forum: GMAT Math
- Topic: need the standard deviation for dummies book
- Replies: 2
- Views: 8360
Everything makes sense except for one part. 2^-at = 2^-1 then at = 1 So are you saying that if X^a = X^b, then a = b? Ok, never mind, writing it like that I now see it. If the bases are the same and the values are the same, then the exponents must also be equal. That is the step I couldn't see when ...
- by allenkt
Sun May 06, 2007 6:34 pm- Forum: Problem Solving
- Topic: GMATPrep exponents question
- Replies: 2
- Views: 1688
The complete question: On a recent trip, Cindy drove her car for 290 miles, rounded to the nearest 10 miles, and used 12 gallons of gasoline, rounded to the nearest gallon. The actual number of miles per gallon that Cindy's car got on this trip must have been between: a) 290/12.5 and 290/11.4 b) 295...
- by allenkt
Sun May 06, 2007 6:23 pm- Forum: Problem Solving
- Topic: seemingly simple rounding question
- Replies: 4
- Views: 2885
GMATPrep multiples question
Is integer n a multiple of 15?
a) n is a multiple of 20
b) n + 6 is a multiple of 3
- by allenkt
Sun May 06, 2007 5:50 pm- Forum: Data Sufficiency
- Topic: GMATPrep multiples question
- Replies: 2
- Views: 2583
GMATPrep function question
This was one of the first questions I had on the GMATPrep and it threw me for a loop. The function f is defined for all positive integers n by the following rule: f(n) is the number of positive integers each of which is less than n and has no positive factor in common with n other than 1. If P is an...
- by allenkt
Sun May 06, 2007 5:47 pm- Forum: Problem Solving
- Topic: GMATPrep function question
- Replies: 1
- Views: 1478
Thanks! I knew there was an easy way but I just couldn't see it. I was trying so hard to factor that I didn't even think of doing it that way.
- by allenkt
Sun May 06, 2007 5:44 pm- Forum: Problem Solving
- Topic: GMATPrep factoring question
- Replies: 2
- Views: 1801
GMATPrep exponents question
I ran into a question on the GMAT prep that I've seen before but I can't seem to find it so I can see how to solve it. I didn't write down the exact question but it was one about figuring out the temperature of a cup of coffee 30 minutes after is was poured given the temp at 10 minutes and a formula...
- by allenkt
Sun May 06, 2007 5:41 pm- Forum: Problem Solving
- Topic: GMATPrep exponents question
- Replies: 2
- Views: 1688
GMATPrep factoring question
This one has me stumped. I know the answer should be 10 but I just can't seem to figure it out. Someone please show me how to solve this one!
1001^2 - 999^2 / 101^2 - 99^2 = ?
At first glance I thought I would factor 100 out of the top and 10 out of the bottom but that didn't work.
- by allenkt
Sun May 06, 2007 5:37 pm- Forum: Problem Solving
- Topic: GMATPrep factoring question
- Replies: 2
- Views: 1801
need the standard deviation for dummies book
I have a very basic understanding of standard deviation but apparently I need more. I've taken both of the GMATPrep tests and both times a standard deviation question appeared near the beginning. And both times I was stumped. Pretty much all I know about standard deviation is that it is a way to exp...
- by allenkt
Sun May 06, 2007 1:29 pm- Forum: GMAT Math
- Topic: need the standard deviation for dummies book
- Replies: 2
- Views: 8360
Probabilities question
Admittedly, probability is a weak area for me because I don't remember ever taking anything like it in high school or college (never took statistics). I have a question about a formula. I recently learned the formula to be as follows: If you have n items, taken r at a time, the total number of possi...
- by allenkt
Sun Apr 29, 2007 7:08 pm- Forum: GMAT Math
- Topic: Probabilities question
- Replies: 1
- Views: 3040
It is my understanding that the questions in the OG get harder as you go along. I am currently on question 110 out of 155 in DS so I guess I'll find out tomorrow!
- by allenkt
Sun Apr 29, 2007 6:59 pm- Forum: GMAT Math
- Topic: OG DS questions
- Replies: 3
- Views: 3770
whew...this one had me stumped for a bit. My mistake was assuming the 1 hour all took place in one call. But to save the maximum amount he would have to make 60 calls, each one minute in duration. Granted, this would also be the plan that would spend the most money, but it's also the one that would ...
- by allenkt
Sun Apr 29, 2007 6:54 pm- Forum: Problem Solving
- Topic: Kaplan CAT - price of telephone call
- Replies: 3
- Views: 1788
seemingly simple rounding question
OG 11, problem solving question #129 seems pretty straightforward: On a recent trip, Cindy drove her car for 290 miles, rounded to the nearest 10 miles, and used 12 gallons of gasoline, rounded to the nearest gallon. The actual number of miles per gallon that Cindy's car got on this trip must have b...
- by allenkt
Sat Apr 28, 2007 3:25 pm- Forum: Problem Solving
- Topic: seemingly simple rounding question
- Replies: 4
- Views: 2885
I may not be the most qualified person to answer this question, but I think if you are not pressed for time and the extra $ (I think it's $50) doesn't bother you then go ahead and wait that extra month. Even if you are ready now, it sounds like you would psych yourself out and do poorly just because...
- by allenkt
Sun Apr 22, 2007 4:36 pm- Forum: GMAT Strategy
- Topic: Last-minute advice needed!
- Replies: 7
- Views: 2965
The answer choices are: a. 16 b. 72 c. 112 d. 128 e. 142 And the correct answer, as you might have guessed is d. I can follow your method much easier than the books. I still don't know where they came up with their method. The book is much more confusing to me. That answer reads as such: From this, ...
- by allenkt
Sat Apr 21, 2007 3:39 pm- Forum: Problem Solving
- Topic: don't understand ratio question
- Replies: 3
- Views: 2285