Compilation of some tough problems

[gmatkn]

This is my First mail in this Forum and it is to YOU.

Thank a lot for compilation.

I did not go through it but thanks to your efforts.

bye

KN

[rv_blitz]

54. Two people walked the same distance, one person's speed is between 25 and 45,and if he used 4 hours, the speed of another people is between 45 and 60,and if he used 2 hours, how long is the distance?
A.116 B.118 C.124 D.136 E.140

Soln : A
Let A be the person walking with speed between 25 and 45. 25<=SpA<=45.
Let B be the person walking with speed between 45 and 60. 45<=SpB<=60.
TimeA = time taken by A to cover the required distance d = 2 hrs.
TimeB = time taken by B to cover the same distance d = 4hrs.

As the distance is same.
(TimeA/TimeB)=(SpB/SpA)=4/2=2/1.
There fore the possible combinnations for SpA,SpB based on the constraints =
(25,50)
(26,52)
(27,54)
(28,56)
(29,58)
(30,60)

As , we know time taken by A = 4hrs, the only answer that matches the option is 29*4=116. Hence , A.

[forthegmat]

I am getting a different answer to question#1.

Sum of even numbers between 1 and n = 2 + 4 + ...+ (n-1)
= 2(1 + 2 + ..(n-1)/2) = (n-1)(n+1)/4
So we get the equation: (n-1)(n+1)/4 = 79*80
which reduces to (n-1)(n+1) = 158*160
from which we get n = 159.

[MAT]

Originally Posted by forthegmat

I am getting a different answer to question#1.

Sum of even numbers between 1 and n = 2 + 4 + ...+ (n-1)
= 2(1 + 2 + ..(n-1)/2) = (n-1)(n+1)/4
So we get the equation: (n-1)(n+1)/4 = 79*80
which reduces to (n-1)(n+1) = 158*160
from which we get n = 159.

• The sum of the even numbers between 1 and n is 79*80, where n is an odd number, then n=?

n*(n+1) = 79 * 80 ==> n =79

[saideep]

guys have my GMAT on the 10th of jan...finding some of these problems real tough to do...am consistantly scoring 48 in my GMAtprep tests and am able to do the GMAT sets under timed conditions getting only 5 wrong or so,

are these real GMAT questions and are we likly to see questions of this level in the exam,kinda nervous after looking at these questions.

[geomatrace]

Can anyone let me know how to download this file? I am trying to follow the footsteps of the legendary TwinnSplitter, but many links are giving me error messages...

[mathphobia]

what program are you looking at BMW?

[Erin]

Locking this thread and deleting about 90 posts with email addresses in them. Please do not post your contact information in posts. If you have questions about downloading, please ask in the feedback forum. Or try searching...