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 350,000 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:

A certain jar contains only b black marbles, w white marbles [#permalink]
16 Nov 2010, 05:43

1

This post received KUDOS

2

This post was BOOKMARKED

00:00

A

B

C

D

E

Difficulty:

65% (hard)

Question Stats:

61% (02:21) correct
39% (01:33) wrong based on 283 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: a certain jar contains [#permalink]
16 Nov 2010, 05:52

10

This post received KUDOS

Expert's post

anilnandyala 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 then the probability that the marble chosen will be white?

(1) r/(b+w) > w/(b+r) (2) b-w > r

The question is \(\frac{R}{R+B+W}>\frac{W}{R+B+W}\) true? Or is \(R>W\) true?

Re: a certain jar contains [#permalink]
16 Nov 2010, 11:40

5

This post received KUDOS

Expert's post

anilnandyala wrote:

a certain jar contains only b black marbles, w white marbles & r red marbles. if one marble is to be chosen random from jar is the probability that the marble chosen will be red greater then the probability the marble chosen is white? a) r/(b+w) > w/(b+r) b) b-w > r

The probability that red marble is chosen will be greater than the probability that white marble is chosen if there are more red marbles than white marbles. So the queestion is just: Is r > w

Statement 1: r/(b + w) > w/(b + r) Cross multiply to get r(b + r) > w(b + w) .... [(b + w) and (b + r) are definitely positive so cross multiplying is not a problem.] Now, if r > w, (b + r) has to be greater than (b + w) If r were less than w, then (b + r) < (b + w) and the left side would have been smaller than the right side. So this implies that r must be greater than w. Sufficient.

Statement 2: b > r + w But we cant compare r and w so not sufficient.

Re: a certain jar contains [#permalink]
23 Nov 2010, 22:36

Bunuel wrote:

anilnandyala wrote:

a certain jar contains only b black marbles, w white marbles & r red marbles. if one marble is to be chosen random from jar is the probability that the marble chosen will be red greater then the probability the marble chosen is white? a) r/(b+w) > w/(b+r) b) b-w > r

A certain jar contains only b black marbles, w white marbles and [#permalink]
22 May 2013, 06:40

lets rephrase the question first. It says IS r/(w+r+b)> w(r+w+b) Cross multiply because we know all the variables are positive. It becomes Is br+r^2> bw+w^2 ?

Statement 1: when cross multiplying we ger br+ r^2 >bw+ w^2........Thus sufficient

Statement 2: clearly insufficient.

Do not forget to press on Kudos button if it helps.... _________________

Do not forget to hit the Kudos button on your left if you find my post helpful.

A jar contains 8 red marbles and y white marbles. If Joan takes [#permalink]
30 Dec 2013, 10:17

Given 8 red marbles and y white marbles. Number of ways you can pick any two marbles is \((8+Y)C2\). Ways of picking 2 red marbles is 8*7 (first time you can pick out of 8 red marbles and second time you can pick one of the remaining 7 marbles). Ways of picking 1 marble of each color. This can happen in 2 ways. 1 way) First pick white and second pick red [y*8 ways] or 2 way) first pick red and second pick white [8*y ways]. So total number of ways to pick two different colors will be \(y*8 + 8*y\) = \(2*8y\)

A jar contains 8 red marbles and y white marbles. If Joan takes 2 random marbles from the jar, is it more likely that she will have 2 red marbles than that she will have one marble of each color?

Question is asking for - is probability of picking 2 red marbles > probability of picking different color marbles, is \(\frac{8*7}{(8+Y)C2} > \frac{2*8y}{(8+Y)C2}\) Therefore, \(y<7/2=3.5\)

(1) y ≤ 8 y can be less than or greater than 3.5 - NS (2) y ≥ 4 y is always greater than 3.5 - S

Re: A certain jar contains only b black marbles, w white marbles [#permalink]
10 Jan 2014, 05:31

anilnandyala 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 then the probability that the marble chosen will be white?

(1) r/(b+w) > w/(b+r) (2) b-w > r

Is r>w?

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

rb + r^2 ? wb + w^2

(r+w)(r-w) > b(w-r)

Now if r-w>0 then w-r < 0 and inequality holds true. Other way around if r-w<0, LHS is negative and RHS is positive and inequality does NOT hold true

So only valid scenario is r-w>0 and thus r>w

Sufficient

(B) Not enough Info

Answer is A

Cheers J

PS. Alternatively, first statement can be treated as

r-w / b+r>0

Well b+r is always positive, thus r-w has to be positive too Then r>w

Re: A certain jar contains only b black marbles, w white marbles [#permalink]
03 Jun 2014, 08:58

let's rephrase the question as "Is no of red marbles > no of white marbles ?"

Stmt1: r/(b+w) > w/(b+r)

There are two possibilities arising from the above statement .

A fraction r/(b+w) is greater than other fraction w/(b+r), if and only if the following 2 conditions are satisfied. a) r>w or b) (b+r) >( b+w) case1 : numerator 'r' is larger than numerator 'w'; case2 : denominator (b+r) > denominator (b+w) ; in either case we get r>w ; hence sufficient;

Stmt2: b-w > r

We can consider two cases(numbers) for which the above statement is both true and false;

case1: b=10; w=2 ; r=7; 10-2>7; r>w(true)

Case2: b=10; w=5; r=4; 10-5>4; but here 4>5(false); Hence Insufficient.

gmatclubot

Re: A certain jar contains only b black marbles, w white marbles
[#permalink]
03 Jun 2014, 08:58

Type of Visa: You will be applying for a Non-Immigrant F-1 (Student) US Visa. Applying for a Visa: Create an account on: https://cgifederal.secure.force.com/?language=Englishcountry=India Complete...