Difficult GMAT Math Problems

beatthegmat · Posted: Sat Apr 15, 2006 3:34 pm Post subject: Difficult GMAT Math Problems

Here's a document with over 100 really tough GMAT math problems. If you can get through these easily, you probably don't need to prep much more for the math section.

isisalaska · Posted: Wed Dec 13, 2006 4:43 pm Post subject: Difficult GMAT Math Problems

are these problems more diffcult than the ones we will find in the GMAT test? are these problems more in line iwth the Kaplan 800 book?
Thanks!

beatthegmat · Posted: Wed Dec 13, 2006 11:43 pm Post subject: Re: Difficult GMAT Math Problems

Kansonne · Posted: Mon Feb 05, 2007 10:02 pm Post subject: First Question

Hi,

Can anyone explain the solution to the first problem in this "gmat MATH tough problems.doc" set?

Here's the problem and solution again:

1. The sum of the even numbers between 1 and n is 79*80, where n is an odd number, then n=?
Sol: First term a=2, common difference d=2 since even number

therefore sum to first n numbers of Arithmetic progression would be

n/2(2a+(n-1)d)

= n/2(2*2+(n-1)*2)=n(n+1) and this is equal to 79*80

therefore n=79 which is odd...

My questions are...

I tried plugging and chugging different values of n into the equation above, for example, n = 3. The sum of even numbers between 1 and 3 is 2, but with the formula in the solution, I get 12. What am I doing wrong?

Thanks!

beatthegmat · Posted: Mon Feb 05, 2007 10:07 pm Post subject:

For your reference, here's the discussion thread for this problem: http://www.beatthegmat.com/viewtopic.php?t=406

Best of luck!

art · Posted: Wed Oct 24, 2007 12:21 pm Post subject: Explanation to solution 1

n is the number of terms in the A.P.

For even numbers between 1 and 3 (which is 2), n is 1 and not 3
Plug this into the formula

ginger · Posted: Wed Feb 20, 2008 2:56 pm Post subject: Need the File

Can someone please email me the file with the difficult questions? It is not opening at all and I cannot open or save it. Thanks alot!

meermaidrose@yahoo.com Smile

workhard_1978 · Posted: Thu Feb 28, 2008 3:33 am Post subject:

Eric,

Where have these questions come from ?Kaplan,Princeton, Manhattan or OG

?

Pls let me know

jbeurg · Posted: Mon May 26, 2008 5:22 am Post subject: Re: Difficult GMAT Math Problems

wilderness · Posted: Fri Jul 18, 2008 6:54 am Post subject:

Dear GMAT Gurus,

I am taking an average of 5 minutes to solve these tough questions. I know the average time we have on GMAT is 2, but I dont expect to have many questions of this difficulty in the exam. While working with OG, my average time is less than 2 min. So the question is

What have been your averge time when you do these questions and do you think average of 5 min per question is acceptable.