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:
Want to score 90 percentile or higher on GMAT CR? Attend this free webinar to learn how to pre-think assumptions and solve the most challenging questions in less than 2 minutes.
Each of the marbles in a jar is either red or white or blue. If one ma
[#permalink]
Show Tags
19 Sep 2015, 12:55
4
19
00:00
A
B
C
D
E
Difficulty:
5% (low)
Question Stats:
93% (00:53) correct 7% (00:59) wrong based on 1560 sessions
HideShow timer Statistics
Each of the marbles in a jar is either red or white or blue. If one marble is to be selected at random from the jar, what is the probability that the marble will be blue?
(1) There are a total of 24 marbles in the jar, 8 of which are red. (2) The probability that the marble selected will be white is 1/2.
Re: Each of the marbles in a jar is either red or white or blue. If one ma
[#permalink]
Show Tags
22 Sep 2015, 01:01
8
2
We need to find the ratio (no. of blue marbles/total marbles). (1) 8 are red. So, 16 are either blue or white. This could mean 0 blue, 16 white or any number for blue upto 16, with 16-blue number of whites. Not sufficient. (2) probability of white is 1/2. So, probability of (blue or red) is 1/2. Now, we don't know the probability of red, so we can't find that of blue. Not sufficient.
(1) and (2) together - probability of white = 1/2. We also know from (1) that there are 24 marbles in all. So, there are 12 white marbles (since 12/24 = 1/2). Out of the remaining, 8 are red, so 4 must be blue. Given this, we can find the probability of blue marbles as 4/24 = 1/6.
Hence, BOTH TOGETHER ARE SUFFICIENT.
_________________
If you like this post, be kind and help me with Kudos!
Affiliations: AB, cum laude, Harvard University (Class of '02)
Joined: 10 Jul 2015
Posts: 706
Location: United States (CA)
Age: 39
GMAT 1: 770 Q47 V48
GMAT 2: 730 Q44 V47
GMAT 3: 750 Q50 V42
GRE 1: Q168 V169
WE: Education (Education)
Re: Each of the marbles in a jar is either red or white or blue. If one ma
[#permalink]
Show Tags
27 Mar 2016, 19:14
Here is a visual that should help.
Attachments
Screen Shot 2016-03-27 at 7.13.14 PM.png [ 432.08 KiB | Viewed 16768 times ]
_________________
Harvard grad and 99% GMAT scorer, offering expert, private GMAT tutoring and coaching worldwide since 2002.
One of the only known humans to have taken the GMAT 5 times and scored in the 700s every time (700, 710, 730, 750, 770), including verified section scores of Q50 / V47, as well as personal bests of 8/8 IR (2 times), 6/6 AWA (4 times), 50/51Q and 48/51V.
You can download my official test-taker score report (all scores within the last 5 years) directly from the Pearson Vue website: https://tinyurl.com/y7knw7bt Date of Birth: 09 December 1979.
Re: Each of the marbles in a jar is either red or white or blue. If one ma
[#permalink]
Show Tags
24 Jul 2017, 11:13
Top Contributor
BrainLab wrote:
Each of the marbles in a jar is either red or white or blue. If one marble is to be selected at random from the jar, what is the probability that the marble will be blue?
(1) There are a total of 24 marbles in the jar, 8 of which are red. (2) The probability that the marble selected will be white is 1/2.
Target question:What is the probability that the marble will be blue?
Given: Each of the marbles in a jar is either red or white or blue.
Statement 1: There are a total of 24 marbles in the jar, 8 of which are red. There are several scenarios that satisfy statement 1. Here are two: Case a: there are 8 red marbles, 3 white marbles and 13 blue marbles. In this case, P(marble is blue) = 13/24 Case b: there are 8 red marbles, 2 white marbles and 14 blue marbles. In this case, P(marble is blue) = 14/24 Since we cannot answer the target question with certainty, statement 1 is NOT SUFFICIENT
Statement 2: The probability that the marble selected will be white is 1/2 No information about the red marbles or blue marbles. So, statement 2 is NOT SUFFICIENT
If you're not convinced, consider These two cases, which lead to different answers to the target question: Case a: there are 8 red marbles, 12 white marbles and 4 blue marbles. Notice that P(white) = 12/24 = 1/2. In this case, P(marble is blue) = 4/24 Case b: there are 11 red marbles, 12 white marbles and 1 blue marble. Notice that P(white) = 12/24 = 1/2. In this case, P(marble is blue) = 1/24 Since we cannot answer the target question with certainty, statement 2 is NOT SUFFICIENT
Statements 1 and 2 combined Statement 1 tells us that there are 24 marbles, and 8 are red Statement 2 tells us that half the marbles are white. So, 12 of the 24 marbles are white. If there are 24 marbles, and 8 are red and 12 are white, then the REMAINING 4 marbles must be blue This means P(marble is blue) = 4/24 = 1/6 Since we can answer the target question with certainty, the combined statements are SUFFICIENT
Re: Each of the marbles in a jar is either red or white or blue. If one ma
[#permalink]
Show Tags
13 Aug 2017, 01:39
Each of the marbles in a jar is either red or white or blue. If one marble is to be selected at random from the jar, what is the probability that the marble will be blue?
(1) There are a total of 24 marbles in the jar, 8 of which are red. We do not know the number of blue marbles. Not sufficient. (2) The probability that the marble selected will be white is 1/2. The probability of selecting Red and Blue is 1/2. But we cannot infer the probability that the marble will be blue. Not sufficient.
From 1 and 2, The number of Red and Blue marbles is 12. The number of red marbles is 8, so number of blue marbles is 4. Sufficient.
Re: Each of the marbles in a jar is either red or white or blue. If one ma
[#permalink]
Show Tags
14 Mar 2019, 03:56
Hello from the GMAT Club BumpBot!
Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).
Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________
close
93% (00:53) correct 
