Events & Promotions
|
|
GMAT 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.
Apr 2610:00 AM EDT
-11:00 AM EDT
The Target Test Prep course represents a quantum leap forward in GMAT preparation, a radical reinterpretation of the way that students should study. Try before you buy with a 5-day, full-access trial of the course for FREE!
Apr 2711:00 AM EDT
-12:00 PM EDT
Prefer video-based learning? The Target Test Prep OnDemand course is a one-of-a-kind video masterclass featuring 400 hours of lecture-style teaching by Scott Woodbury-Stewart, founder of Target Test Prep and one of the most accomplished GMAT instructors
Apr 2808:00 AM PDT
-11:00 AM PDT
Whether you are just beginning your MBA journey or fine-tuning your path to a 700+ score, GMAT Day is designed to give you a competitive edge.
02 Mar 2021, 05:00
Kudos
Bookmarks
B
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
65%
(hard)
Question Stats:
60% (02:28) correct
40%
(02:38)
wrong
based on 121
sessions
History
Date
Time
Result
Not Attempted Yet
If the probabilities that three students A, B and C may pass the exam are 4/7, 3/5, and 2/3, respectively. What is the probability that at least two pass ?
(A) 33/35
(B) 2/3
(C) 2/5
(D) 29/105
(E) 8/35
(A) 33/35
(B) 2/3
(C) 2/5
(D) 29/105
(E) 8/35
02 Mar 2021, 06:53
Kudos
Bookmarks
Hi Bunuel. Could you please recheck the answer options. IMO it should b 2/3.
P(A Passes) = 4/7. Therefore P(A Fails) = P(A') = 1 - (4/7) = 3/7
P(B Passes) = 3/5. Therefore P(B Fails) = P(B') = 1 - (3/5) = 2/5
P(C Passes) = 2/3. Therefore P(C Fails) = P(C') = 1 - (2/3) = 1/3
P(At least 2 passes) = exactly 2 pass + all 3 pass
P(Only 2 students pass) = A and B passes, C Fails + A and C passes, B fails + B and C passes, A Fails
= (4/7 * 3/5 * 1/3) + (4/7 * 2/5 * 2/3) + (3/7 * 3/5 * 2/3) = 12/105 + 16/105 + 18/105 = 46/105
P(All 3 pass) = 4/7 * 3/5 * 2/3 = 24/105
The required probability = 46/105 + 24/105 = 70/105 = 2/3
Arun Kumar
P(A Passes) = 4/7. Therefore P(A Fails) = P(A') = 1 - (4/7) = 3/7
P(B Passes) = 3/5. Therefore P(B Fails) = P(B') = 1 - (3/5) = 2/5
P(C Passes) = 2/3. Therefore P(C Fails) = P(C') = 1 - (2/3) = 1/3
P(At least 2 passes) = exactly 2 pass + all 3 pass
P(Only 2 students pass) = A and B passes, C Fails + A and C passes, B fails + B and C passes, A Fails
= (4/7 * 3/5 * 1/3) + (4/7 * 2/5 * 2/3) + (3/7 * 3/5 * 2/3) = 12/105 + 16/105 + 18/105 = 46/105
P(All 3 pass) = 4/7 * 3/5 * 2/3 = 24/105
The required probability = 46/105 + 24/105 = 70/105 = 2/3
Arun Kumar
wishmasterdj
Joined: 04 May 2016
Last visit: 25 Oct 2021
Posts: 91
Own Kudos:
Given Kudos: 10
Location: India
Schools: ISB '18 (A)
GMAT 1: 700 Q48 V37
GPA: 3.2
10 Mar 2021, 06:20
Kudos
Bookmarks
Is there some 'smartness' GMAT wants to test with this question? I think this is a very straight forward yet mechanical question. Would you agree?
