GRE Prep 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
Track
Your Progress
Practice
Pays
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
A box contains 5 green balls, 3 black balls and 2 red balls. If 2 bal
[#permalink]
12 Nov 2024, 00:20
12 Nov 2024, 00:20
Expert Reply
00:00
Question Stats:
100% (00:56) correct
0% (00:00) wrong based on 2 sessions
Hide Show timer Statistics
A box contains 5 green balls, 3 black balls and 2 red balls. If 2 balls are taken out of the box successively without replacement, what is the probability that the two balls are red?
A. 1/45
B. 2/45
C. 1/15
D. 4/45
E. 1/9
A. 1/45
B. 2/45
C. 1/15
D. 4/45
E. 1/9
- Part of the project: GRE Quant & Verbal ADVANCED Daily Challenge 2024 Edition - Gain 20 Kudos & Get FREE Access to GRE Prep Club TESTS
- Also replying to the unanswered questions
Re: A box contains 5 green balls, 3 black balls and 2 red balls. If 2 bal
[#permalink]
15 Nov 2024, 16:38
15 Nov 2024, 16:38
1
5 green balls, 3 black balls, and 2 red balls (10 balls total)
Ball grab #1. Probability that the first ball taken out of the box is red = 2/10 (out of all the balls, 2 are red)
To successfully pull two balls in a row that are red, Ball Grab #1 must be red. The ball is not replaced, so there are 9 balls left in the bag and only 1 red ball is left in the bag (since we pulled the other red ball in ball grab #1).
Ball Grab #2. Probability that the 2nd ball taken out of the box is red = 1/9.
Multiply these probabilities together:
(2/10) x (1/9) = 9/20 (simplified to 1/45 to match the answer choices).
Answer is A
Ball grab #1. Probability that the first ball taken out of the box is red = 2/10 (out of all the balls, 2 are red)
To successfully pull two balls in a row that are red, Ball Grab #1 must be red. The ball is not replaced, so there are 9 balls left in the bag and only 1 red ball is left in the bag (since we pulled the other red ball in ball grab #1).
Ball Grab #2. Probability that the 2nd ball taken out of the box is red = 1/9.
Multiply these probabilities together:
(2/10) x (1/9) = 9/20 (simplified to 1/45 to match the answer choices).
Answer is A
gmatclubot
Re: A box contains 5 green balls, 3 black balls and 2 red balls. If 2 bal [#permalink]
15 Nov 2024, 16:38
Moderators:
