BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

Probability_blue marble

Expert replies
by Soumita Ghosh » Sun Feb 03, 2013 7:51 pm
(1) The probability of drawing one blue marble is 6/35 .
(2) The probability of drawing no blue marbles is 4/35 .

What is the probability of drawing at least two blue marbles from a jar if three marbles are chosen?\

A.The probability of drawing one blue marble is .

B.The probability of drawing one blue marble is .

C.BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.

D.EACH statement ALONE is sufficient.

E.Statements (1) and (2) TOGETHER are NOT sufficient.

OA C

Bu my choice is D

From Statement A:

It is given the probability of drawing blue marble which is 6/35. From here we can find the probability of not drawing blue marble is 1-6/35=29/35

so from here we can find the probability at least two blue marbles from a jar if three marbles are chosen.

6/35*6/35*29/35 + 6/35*6/35*6/35

so statement A is sufficient

From Statement B:

The probability of drawing no blue marbles is 4/35. From here we can find the probability of drawing blue marble which is 1-4/35=31/35

So from here we can find the probability of at least two blue marbles from a jar if three marbles are chosen

So statement B is sufficient.

Therefore each statement is sufficient.

Please explain me where I am wrong!!
Join the discussion
Source: — Data Sufficiency |

by Jim@StratusPrep » Mon Feb 04, 2013 8:10 am
I drop you a hint to start the conversation.... These probabilities are not for drawing 1 marble at a time, but rather 1 blue marble out of 3 or no blue marbles out of 3. We don't know the number of marbles or blue marbles in the jar...


Does that help?

I can keep going, but want to give you the opportunity to think it through...
GMAT Answers provides a world class adaptive learning platform.
-- Push button course navigation to simplify planning
-- Daily assignments to fit your exam timeline
-- Organized review that is tailored based on your abiility
-- 1,000s of unique GMAT questions
-- 100s of handwritten 'digital flip books' for OG questions
-- 100% Free Trial and less than $20 per month after.
-- Free GMAT Quantitative Review

Image
Join the discussion

by Soumita Ghosh » Mon Feb 04, 2013 3:17 pm
Hi Jim,

thanks for your response !!

It is still not clear to me.

As per my understanding as we don't know the number of marbles or blue marbles in the jar we cannot find the probability from each statement alone.Then how can both statement is sufficient?

Please clear me !! I not good in probability !!

Is there any difference in meaning between the sentence the probability of drawing blue marble and the probability of drawing one blue marble?
Join the discussion