Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized for You

we will pick new questions that match your level based on your Timer History

Track Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice Pays

we will pick new questions that match your level based on your Timer History

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

It appears that you are browsing the GMAT Club forum unregistered!

Signing up is free, quick, and confidential.
Join other 500,000 members and get the full benefits of GMAT Club

Registration gives you:

Tests

Take 11 tests and quizzes from GMAT Club and leading GMAT prep companies such as Manhattan GMAT,
Knewton, and others. All are free for GMAT Club members.

Applicant Stats

View detailed applicant stats such as GPA, GMAT score, work experience, location, application
status, and more

Books/Downloads

Download thousands of study notes,
question collections, GMAT Club’s
Grammar and Math books.
All are free!

Thank you for using the timer!
We noticed you are actually not timing your practice. Click the START button first next time you use the timer.
There are many benefits to timing your practice, including:

Re: Problem Solving for 780+ Aspirants [#permalink]

Show Tags

11 May 2009, 20:25

walker wrote:

GMAT TIGER wrote:

But walker how did you get 64 and 16? Why you multiplied by 2 in both cases?

I remember that GMAT always says "number of positive factors" to avoid ambiguity. So, I used "2" to count both negative and positive set of factors. Anyway, it would be better to use word "positive" in the question.

Re: Problem Solving for 780+ Aspirants [#permalink]

Show Tags

07 Oct 2009, 13:04

cicerone wrote:

Folks, here is the next question..

From the set of positive factors of 840 one factor is chosen at random. What is the probability that it is divisible by 15?

A. 1/4

B. 7/32

C. 1/2

D. 1/56

E. None of these

my approach : total no of factors =(2^3)*3*5*7=refer powers (3+1)x(1+1)x(1+1)x(1+1)=32 factors we want to select factors divisible by 15 ie 3 x 5 should be part of all divisors..we can ensure that by neglecting 3^0 & 5^0 in each factor i.e. = (2^0+2^1+2^2+2^3) * (3^1) * (5^1) * (7^0+7^1) = thus no of factors factors 4x1x1x2 = 8 factors [15 , 15x7, 15x2, 15x4, 15x8, 15x7x2, 15x7x4, 15x7x8]

prob = 8/32 = 1/4 OA A _________________

Bhushan S. If you like my post....Consider it for Kudos

Walker...i think we should multiply it by 2 for same color and different color individually because we might get 2 blacks or 2 reds. So prob will be 2(1000/2001) and 2(1001/2001)

And the final answer would be 2/2001

gmatclubot

Re: Problem Solving for 780+ Aspirants
[#permalink]
04 Nov 2013, 09:25

This is the kickoff for my 2016-2017 application season. After a summer of introspect and debate I have decided to relaunch my b-school application journey. Why would anyone want...

Check out this awesome article about Anderson on Poets Quants, http://poetsandquants.com/2015/01/02/uclas-anderson-school-morphs-into-a-friendly-tech-hub/ . Anderson is a great place! Sorry for the lack of updates recently. I...

Time is a weird concept. It can stretch for seemingly forever (like when you are watching the “Time to destination” clock mid-flight) and it can compress and...