I'm posting here the Qs i got wrong and am not sure how to answer. Hope you could help me out.
1) Is m + z > 0
a) m-3z > 0
b) 4z - m >0
2) The perimeter of a certain isosceles triangle is 16 + 16 (square root of 2). What is the length of the hypotenuse of the triangle?
3) If the terms of a sequence are t1, t2, t3,..., tn, what is the value of n?
a) The sum of the n terms is 3,124
b) The average (arithmetic mean) of the n terms is 4
4) A certain stock exchange designates each stock with a 1, 2 or 3-letter code, where each letter is selected from the 26 letters of the alphabet. If the letters may be repeated and if the same letters used in a different order constitute a different order, how many different stocks is it possible to uniquely designate with these codes?
5) If ax + b = 0, is x > 0 ?
a) a +b > 0
b) a - b > 0
6) A company has two types of machines, type R and type S. Operating at a constant rate, a machine of type R does a certain job in 36 hours and a machine of type S does the same job in 18 hours. If the company used the same number of each type of machine to the job in 2 hours, how many machines of type R were used?
7) Three grades of milk are 1 percent, 2 percent, and 3 percent fat by volume. If x gallons of the 1 percent grade, y gallons of the 2 percent grade, and z gallons of the 3 percent grade are mixed to give x+ y + z gallons of a 1.5 percent grade, what is x in terms of y and z?
8) On the number line, the distance between x and y is greater than the distance between x and z. Does z lie between x and y on the number line?
a) xyz < 0
b) xy < 0
9) When a certain tree was first planted, it was 4 feet tall, and the height of the tree increased by a constant amount each year for the next 6 years. At the end of the 6th year, the tree was 1/5 taller than it was at the end of the 4th year. By how many feet did the height of the tree increase each year?
10) For which of the following functions is f(a+b) = f(a) + f(b) for all positive numbers a and b?
a) f(x) = x^2
b) f(x) = x +1
c) f(x) = (square root of x)
d) f(x) = 2/x
e) f(x) = -3x
11) If the speed of x meters per second is equivalent to the speed of y kilometers per hour, what is y in terms of x?
12) Jason's salary and Karen's salary were each p percent greater in 1998 than in 1995. What is the value of p?
a) In 1995, Karen's salary was $2,000 greater than Jason's
b) In 1998, Karen's salary was $2,400 greater than Jason's
13) Each person attending a fund-raising party for a certain club was charged the same admission fee. How many people attended the party?
a) If the admission fee had been $0.75 less and 100 more people had attended, the club would have received the same amount in admission fees.
b) If the admission fee had been $1.50 more and 100 fewer people had attended, the club would have received the same amount in admission fees.
HELP!!!
GMATPrep Mistakes
This topic has expert replies
GMAT/MBA Expert
- Anju@Gurome
- GMAT Instructor
- Posts: 511
- Joined: Wed Aug 11, 2010 9:47 am
- Location: Delhi, India
- Thanked: 344 times
- Followed by:86 members
Please do not post so many problems in one thread. It'll be a mess if different people have doubts in different solutions. Also most of the GMATPrep problems have been discussed in this forum quite a number of times. Just use the search facility of the forum; It is likely that you will get a solution that suits you.
And there are separate forums for PS and DS problems. This forum is mainly for general quant discussions. You'll get much more response if you post the problems in the correct forum.
I'll post the solution of first problem only.
Make separate threads for other problems if you cannot find their solutions.
Consider the following two cases,
Statement 1: 4z > m
Consider the following two cases,
1 & 2 Together: As m > 3z and m < 4z, 3z must be less than 4z.
This is only possible if z is positive.
Now, z > 0 and m > 3z.
So, m > 3z > 0
--> (m + z) > 0
Sufficient
[spoiler]
The correct answer is C.[/spoiler]
And there are separate forums for PS and DS problems. This forum is mainly for general quant discussions. You'll get much more response if you post the problems in the correct forum.
I'll post the solution of first problem only.
Make separate threads for other problems if you cannot find their solutions.
Statement 1: m > 3zactofman wrote:Is m + z > 0
a) m-3z > 0
b) 4z - m >0
Consider the following two cases,
- m = 1, z = 0 ---> (m + z) = (1 + 0) = 1 > 0 ---> YES
m = 0, z = -1 ---> (m + z) = (0 - 1) = -1 < 0 ---> NO
Statement 1: 4z > m
Consider the following two cases,
- m = 0, z = 1 ---> (m + z) = (0 + 1) = 1 > 0 ---> YES
m = -1, z = 0 ---> (m + z) = (-1 + 0) = -1 < 0 ---> NO
1 & 2 Together: As m > 3z and m < 4z, 3z must be less than 4z.
This is only possible if z is positive.
Now, z > 0 and m > 3z.
So, m > 3z > 0
--> (m + z) > 0
Sufficient
[spoiler]
The correct answer is C.[/spoiler]
Anju Agarwal
Quant Expert, Gurome
Backup Methods : General guide on plugging, estimation etc.
Wavy Curve Method : Solving complex inequalities in a matter of seconds.
§ GMAT with Gurome § Admissions with Gurome § Career Advising with Gurome §
Quant Expert, Gurome
Backup Methods : General guide on plugging, estimation etc.
Wavy Curve Method : Solving complex inequalities in a matter of seconds.
§ GMAT with Gurome § Admissions with Gurome § Career Advising with Gurome §
- faraz_jeddah
- Master | Next Rank: 500 Posts
- Posts: 358
- Joined: Thu Apr 18, 2013 9:46 am
- Location: Jeddah, Saudi Arabia
- Thanked: 42 times
- Followed by:7 members
- GMAT Score:730
Sides are in the ratio of x: x : x*sq.rt 2actofman wrote:I'm posting here the Qs i got wrong and am not sure how to answer. Hope you could help me out.
2) The perimeter of a certain isosceles triangle is 16 + 16 (square root of 2). What is the length of the hypotenuse of the triangle?
HELP!!!
2x + x*sqrt 2 = 16 + 16*sqrt 2
solve for x and multiply by sqrt.2
- faraz_jeddah
- Master | Next Rank: 500 Posts
- Posts: 358
- Joined: Thu Apr 18, 2013 9:46 am
- Location: Jeddah, Saudi Arabia
- Thanked: 42 times
- Followed by:7 members
- GMAT Score:730
What we need is the number of termsactofman wrote:
3) If the terms of a sequence are t1, t2, t3,..., tn, what is the value of n?
a) The sum of the n terms is 3,124
b) The average (arithmetic mean) of the n terms is 4
1 doesnt tell you about the interval or the average. => Not Sufficient
2 Gives you the average but nothing about sum. => Not sufficient
1 and 2 together
Sum (3124) /n = 4
n = 3124/4 = 781
IMO Answer is C
- faraz_jeddah
- Master | Next Rank: 500 Posts
- Posts: 358
- Joined: Thu Apr 18, 2013 9:46 am
- Location: Jeddah, Saudi Arabia
- Thanked: 42 times
- Followed by:7 members
- GMAT Score:730
# of 1 letter codes = number of alphabets = 26actofman wrote: 4) A certain stock exchange designates each stock with a 1, 2 or 3-letter code, where each letter is selected from the 26 letters of the alphabet. If the letters may be repeated and if the same letters used in a different order constitute a different order, how many different stocks is it possible to uniquely designate with these codes?
# of 2 letter codes = 26*26 (since each alphabet can be repeated)
# of 3 letter codes = 26^3
Total = 26 + 26^2 + 26^3 = 26( 1 + 26 +26^2) = 18,278 (a short cut could be to see any of the answer choices end with 8)
Apologies and thanks!
Anju@Gurome wrote:Please do not post so many problems in one thread. It'll be a mess if different people have doubts in different solutions. Also most of the GMATPrep problems have been discussed in this forum quite a number of times. Just use the search facility of the forum; It is likely that you will get a solution that suits you.
And there are separate forums for PS and DS problems. This forum is mainly for general quant discussions. You'll get much more response if you post the problems in the correct forum.
I'll post the solution of first problem only.
Make separate threads for other problems if you cannot find their solutions.
Statement 1: m > 3zactofman wrote:Is m + z > 0
a) m-3z > 0
b) 4z - m >0
Consider the following two cases,Not sufficient
- m = 1, z = 0 ---> (m + z) = (1 + 0) = 1 > 0 ---> YES
m = 0, z = -1 ---> (m + z) = (0 - 1) = -1 < 0 ---> NO
Statement 1: 4z > m
Consider the following two cases,Not sufficient
- m = 0, z = 1 ---> (m + z) = (0 + 1) = 1 > 0 ---> YES
m = -1, z = 0 ---> (m + z) = (-1 + 0) = -1 < 0 ---> NO
1 & 2 Together: As m > 3z and m < 4z, 3z must be less than 4z.
This is only possible if z is positive.
Now, z > 0 and m > 3z.
So, m > 3z > 0
--> (m + z) > 0
Sufficient
[spoiler]
The correct answer is C.[/spoiler]
Oh gosh. That simple? I always get confused with counting problems, whether permutations or combinations. I was initially solving this as 26! + 26!/2! + 26!/3!.faraz_jeddah wrote:# of 1 letter codes = number of alphabets = 26actofman wrote: 4) A certain stock exchange designates each stock with a 1, 2 or 3-letter code, where each letter is selected from the 26 letters of the alphabet. If the letters may be repeated and if the same letters used in a different order constitute a different order, how many different stocks is it possible to uniquely designate with these codes?
# of 2 letter codes = 26*26 (since each alphabet can be repeated)
# of 3 letter codes = 26^3
Total = 26 + 26^2 + 26^3 = 26( 1 + 26 +26^2) = 18,278 (a short cut could be to see any of the answer choices end with 8)
Somehow I got stuck thinking the solution was n(n+1)/2. Well, duh, we're looking for n. Of course it wouldn't work. My bad.faraz_jeddah wrote:What we need is the number of termsactofman wrote:
3) If the terms of a sequence are t1, t2, t3,..., tn, what is the value of n?
a) The sum of the n terms is 3,124
b) The average (arithmetic mean) of the n terms is 4
1 doesnt tell you about the interval or the average. => Not Sufficient
2 Gives you the average but nothing about sum. => Not sufficient
1 and 2 together
Sum (3124) /n = 4
n = 3124/4 = 781
IMO Answer is C
The answer to this is 16. I got confused because I tend to think that 16*sqrt2 is the hypotenuse. Thinking that it goes 1:1:1*sqrt 2, and 2 sides of triangle to be 8 each (hence 16), hypotenuse was 16*sqrt2. But again it's 16. So with things reversed, I'm confused.faraz_jeddah wrote:Sides are in the ratio of x: x : x*sq.rt 2actofman wrote:I'm posting here the Qs i got wrong and am not sure how to answer. Hope you could help me out.
2) The perimeter of a certain isosceles triangle is 16 + 16 (square root of 2). What is the length of the hypotenuse of the triangle?
HELP!!!
2x + x*sqrt 2 = 16 + 16*sqrt 2
solve for x and multiply by sqrt.2
- faraz_jeddah
- Master | Next Rank: 500 Posts
- Posts: 358
- Joined: Thu Apr 18, 2013 9:46 am
- Location: Jeddah, Saudi Arabia
- Thanked: 42 times
- Followed by:7 members
- GMAT Score:730
actofman wrote:The answer to this is 16. I got confused because I tend to think that 16*sqrt2 is the hypotenuse. Thinking that it goes 1:1:1*sqrt 2, and 2 sides of triangle to be 8 each (hence 16), hypotenuse was 16*sqrt2. But again it's 16. So with things reversed, I'm confused.faraz_jeddah wrote:Sides are in the ratio of x: x : x*sq.rt 2actofman wrote:I'm posting here the Qs i got wrong and am not sure how to answer. Hope you could help me out.
2) The perimeter of a certain isosceles triangle is 16 + 16 (square root of 2). What is the length of the hypotenuse of the triangle?
HELP!!!
2x + x*sqrt 2 = 16 + 16*sqrt 2
solve for x and multiply by sqrt.2
take each side as x * sq.rt 2 hence hypotenuse = 2x (we are still maintaining the ratios)
P = 2(x * sq.rt 2) + 2x = 16 + 16 * sq.rt2
=> 2x*sq.rt 2 + 2x = 16 + 16* sq.rt 2
By comparison 2x = 16 ; which is what we need.
Unconventional but it works.