Last visit was: 25 Apr 2026, 06:25 It is currently 25 Apr 2026, 06:25
Close
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

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.
Close
Request Expert Reply
Confirm Cancel
User avatar
EgmatQuantExpert
User avatar
e-GMAT Representative
Joined: 04 Jan 2015
Last visit: 02 Apr 2024
Posts: 3,657
Own Kudos:
20,882
 [16]
Given Kudos: 165
Expert
Expert reply
Posts: 3,657
Kudos: 20,882
 [16]
1
Kudos
Add Kudos
15
Bookmarks
Bookmark this Post
User avatar
EgmatQuantExpert
User avatar
e-GMAT Representative
Joined: 04 Jan 2015
Last visit: 02 Apr 2024
Posts: 3,657
Own Kudos:
20,882
 [2]
Given Kudos: 165
Expert
Expert reply
Posts: 3,657
Kudos: 20,882
 [2]
1
Kudos
Add Kudos
1
Bookmarks
Bookmark this Post
User avatar
pushpitkc
Joined: 26 Feb 2016
Last visit: 19 Feb 2025
Posts: 2,800
Own Kudos:
6,235
 [1]
Given Kudos: 47
Location: India
GPA: 3.12
Posts: 2,800
Kudos: 6,235
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
User avatar
viv007
Joined: 26 Sep 2017
Last visit: 03 Dec 2018
Posts: 81
Own Kudos:
35
 [1]
Given Kudos: 84
Posts: 81
Kudos: 35
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
EgmatQuantExpert
3 deadly mistakes you must avoid in Probability - Exercise Question #3


3- Mark, Peter and David are trying to solve a probability problem. If the probability that Mark, Peter and David can solve the problem correctly is 1/5, 3/7, and 2/6 respectively.
What is the probability that exactly one student cannot solve the problem.

Options
    a) 10/105
    b) 16/105
    c) 22/105
    d) 27/105
    e) 30/105

the easiest way to solve these kind of problem..

prob. of exactly one student cannot solve but we don't know whose the unlucky one ...
we have to take 3 cases and then add all the cases for required prob.

(1-1/5)*3/7*2/6 + 1/5*(1-3/7)*2/6 + 1/5*3/7*(1-2/6) = 22/105
ans C.
avatar
zishu912
Joined: 31 Jan 2018
Last visit: 02 Nov 2019
Posts: 52
Own Kudos:
Given Kudos: 39
GMAT 1: 700 Q46 V40
GMAT 1: 700 Q46 V40
Posts: 52
Kudos: 35
Kudos
Add Kudos
Bookmarks
Bookmark this Post
EgmatQuantExpert
3 deadly mistakes you must avoid in Probability - Exercise Question #3


3- Mark, Peter and David are trying to solve a probability problem. If the probability that Mark, Peter and David can solve the problem correctly is 1/5, 3/7, and 2/6 respectively.
What is the probability that exactly one student cannot solve the problem.

Options
    a) 10/105
    b) 16/105
    c) 22/105
    d) 27/105
    e) 30/105

To solve question 4: Question 4

Probability that Mark and peter solve it correctly, and David solve it incorrectly = 1/5 * 3/7 * 4/6 = 12/210
Next, Probability that Mark and David solve it correctly, Peter solve it incorrectly = 1/5 * 2/6 * 4/7 =8/210
Probability that David and Peter will solve it correctly, and Mark will solve it incorrectly = 3/7 * 2/6 * 4/5 = 24/210

Therefore Probability that exactly one of them will answer incoreectly = 12/210 + 8/210 + 24/210 = 44/210 = 22/105,

Hence Our answer will be (D)
User avatar
EgmatQuantExpert
User avatar
e-GMAT Representative
Joined: 04 Jan 2015
Last visit: 02 Apr 2024
Posts: 3,657
Own Kudos:
Given Kudos: 165
Expert
Expert reply
Posts: 3,657
Kudos: 20,882
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Hey everyone,

The official answer to the question has been posted.

Regards,
Ashutosh
User avatar
bumpbot
User avatar
Non-Human User
Joined: 09 Sep 2013
Last visit: 04 Jan 2021
Posts: 38,981
Own Kudos:
Posts: 38,981
Kudos: 1,117
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Automated notice from GMAT Club BumpBot:

A member just gave Kudos to this thread, showing it’s still useful. I’ve bumped it to the top so more people can benefit. Feel free to add your own questions or solutions.

This post was generated automatically.
Moderators:
Math Expert
109827 posts
Tuck School Moderator
852 posts