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.

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:

A certain jar contains only b black marbles, w white marbles [#permalink]
26 Dec 2007, 19:07

1

This post received KUDOS

1

This post was BOOKMARKED

00:00

A

B

C

D

E

Difficulty:

55% (hard)

Question Stats:

60% (02:27) correct
40% (01:30) wrong based on 164 sessions

A certain jar contains only b black marbles, w white marbles and r red marbles. If one marble is to be chosen at random from the jar, is the probability that the marble chosen will be red greater then the probability that the marble chosen will be white?

Re: DS - Probability [#permalink]
25 Aug 2008, 10:13

jimjohn wrote:

A certain jar contains only b black marbles, w white marbles, and r red marbles. If one marble is to be chosen at random from the jar, is the probability that the marble chosen will be red greater than the probability that the marble chosen will be white?

1) r / (b+w) > w / (b+r)

2) b-w > r

1) r / (b+w) > w / (b+r) r(b+r) > w(b+w) ... this is possible only if r>w. suffcieint

2) b-w > r w >r or w<r INSUFFCIENT.

A _________________

Your attitude determines your altitude Smiling wins more friends than frowning

Re: DS - Probability [#permalink]
27 Sep 2009, 10:44

A certain jar contains only b black marbles, w white marbles, and r red marbles. If one marble is to be chosen at random from the jar, is the probability that the marble chosen will be red greater than the probability that the marble chosen will be white?

1) r / (b+w) > w / (b+r)

2) b-w > r

Soln. From statements what we need to find is i.e if P(choosing one red) > P(choosing one white) i.e if r / (b+w+r) > w / (b+w+r) or in its simplest form after cancelling out the denominators, if r > w

Statement 1 alone is sufficient. Given that => r / (b+w) > w / (b+r) => (b+r)/w > (b+w)/r adding 1 to both sides and taking common denominator => (b+r+w)/w > (b+w+r)/r cancelling numerators and taking r and w to numerators => r > w

Statement 2 alone is not sufficient Given that => b-w > r from this we cannot find if r > w or r < w Hence not sufficient

Re: DS - Probability [#permalink]
15 Feb 2010, 15:16

jimjohn wrote:

A certain jar contains only b black marbles, w white marbles, and r red marbles. If one marble is to be chosen at random from the jar, is the probability that the marble chosen will be red greater than the probability that the marble chosen will be white?

1) r / (b+w) > w / (b+r)

2) b-w > r

Ques: Is r /(b+w+r) > w /(b+w+r) ? or rb + rw + r^2 > wb + w^2 + rw? or rb + r^2 > wb + w^2 ?

S1: r / (b+w) > w / (b+r) rb + r^2 > wb + w^2... Hence SuFF..

S2: b-w>r b > r + w..... this doesnt give r > w or not..... hence INSUFF.

Therefore A. _________________

Cheers! JT........... If u like my post..... payback in Kudos!!

|Do not post questions with OA|Please underline your SC questions while posting|Try posting the explanation along with your answer choice| |For CR refer Powerscore CR Bible|For SC refer Manhattan SC Guide|

Re: DS - Probability [#permalink]
15 Feb 2010, 15:39

jimjohn wrote:

A certain jar contains only b black marbles, w white marbles, and r red marbles. If one marble is to be chosen at random from the jar, is the probability that the marble chosen will be red greater than the probability that the marble chosen will be white?

1) r / (b+w) > w / (b+r)

2) b-w > r

(i) is sufficient because it gives us r<w. Thus we know the answer. From (ii) we can'tsay whether w>r or r>w. Therefore "A"

Re: DS - Probability [#permalink]
17 Feb 2010, 13:53

Damn I'm so bad at DS and inequalities.... scthakur's solution was the easiest for me to understand. Do you guys actually see the answer intuitively without going all the way to the end?