GMAT Question of the Day - Daily to your Mailbox; hard ones only

It is currently 22 Jun 2018, 13:59

Close

GMAT Club Daily Prep

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.

Close

Request Expert Reply

Confirm Cancel

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

A certain jar contains only B black marbles, W white

  post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
Manager
Manager
User avatar
Affiliations: CFA L3 Candidate, Grad w/ Highest Honors
Joined: 03 Nov 2007
Posts: 129
Location: USA
Schools: Chicago Booth R2 (WL), Wharton R2 w/ int, Kellogg R2 w/ int
WE 1: Global Operations (Futures & Portfolio Financing) - Hedge Fund ($10bn+ Multi-Strat)
WE 2: Investment Analyst (Credit strategies) - Fund of Hedge Fund ($10bn+ Multi-Strat)
A certain jar contains only B black marbles, W white [#permalink]

Show Tags

New post 02 Aug 2009, 13:37
00:00
A
B
C
D
E

Difficulty:

(N/A)

Question Stats:

100% (00:00) correct 0% (00:00) wrong based on 0 sessions

HideShow timer Statistics

A certain jar contains only B black marbles, W white marbles, and R red marbles. If one marble is taken out of the jar, is the probability that a red marble is chosen greater then the probability that a white marble is chosen?

(1) R/(B + W) > W/(B + R)

(2) (B - W) > R

Can't figure out how to solve algebraically :(

--== Message from GMAT Club Team ==--

This is not a quality discussion. It has been retired.

If you would like to discuss this question please re-post it in the respective forum. Thank you!

To review the GMAT Club's Forums Posting Guidelines, please follow these links: Quantitative | Verbal Please note - we may remove posts that do not follow our posting guidelines. Thank you.
1 KUDOS received
Intern
Intern
avatar
Joined: 02 Aug 2009
Posts: 3
Schools: McCombs '17
Re: Difficult probability Question (at least for me!) [#permalink]

Show Tags

New post 02 Aug 2009, 14:30
1
To tell whether or not red is more likely to be chosen we need to know if there are more red marbles or white marbles. Plugging in random numbers is likely to be the best way to solve the problem.

If B=1, R=5, W=10, then we will have 5/(1+10) > 10/(1+10) or 5/11 > 10/11. Obviously, this isn't true. So R is unlikely to be smaller than W.

If we do it again, B=1, R=5, W=2, then we will have, 5/(1+2) > 2/(1+5) or 5/3 > 2/6. This is true so (1) is sufficient to tell us that there are more red marbles than white marbles.

For (2) (B-W) > R doesn't tell us anything about the relationship between W and R because the size of B will interfere in determining whether or not R or W is larger.


Hopefully that helped.

--== Message from GMAT Club Team ==--

This is not a quality discussion. It has been retired.

If you would like to discuss this question please re-post it in the respective forum. Thank you!

To review the GMAT Club's Forums Posting Guidelines, please follow these links: Quantitative | Verbal Please note - we may remove posts that do not follow our posting guidelines. Thank you.
Re: Difficult probability Question (at least for me!)   [#permalink] 02 Aug 2009, 14:30
Display posts from previous: Sort by

A certain jar contains only B black marbles, W white

  post reply Question banks Downloads My Bookmarks Reviews Important topics  


cron

GMAT Club MBA Forum Home| About| Terms and Conditions and Privacy Policy| GMAT Club Rules| Contact| Sitemap

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne

Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.