Last visit was: 23 Apr 2026, 10:40 It is currently 23 Apr 2026, 10:40
Home
Messages
Tests
Schools
Events
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.
Go to My Error Log Learn more
Close
Request Expert Reply
Confirm Cancel
Back to Forum
Create Topic
User avatar
tirupatibalaji
User avatar
Joined: 21 May 2010
Last visit: 17 Aug 2012
Posts: 87
Own Kudos:
72
 [14]
Status:Preparing for GMAT - March 2011
Location: London
Concentration: finance
Schools:INSEAD, RSM, HEC, St. Gallen, IF, IESE
WE 1: Finance 6 years
Posts: 87
Kudos: 72
 [14]
A certain class consists of 8 students, including Don. Each 01 Mar 2011, 04:39
Kudos
Add Kudos
14
Bookmarks
Bookmark this Post
00:00
Start Timer
Pause Timer
Resume Timer
Show Answer
Hide
Show
History
B
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!

Difficulty:

45% (medium)

Question Stats:

70% (02:07) correct 30% (02:12) wrong based on 292 sessions

History

Date
Time
Result
Not Attempted Yet
A certain class consists of 8 students, including Don. Each day, three tasks must be completed and are assigned as follows: one of the 8 students is selected at random to complete Task A, one of the remaining 7 students is selected at random to complete Task B, and one of the remaining six students is selected at random to complete Task C. What is the probability that Don will be selected to complete one of the three tasks?

A. 1/3
B. 3/8
C. 1/24
D. 1/336
E. 1/512
ShowHide Answer
Official Answer
B
User avatar
fluke
User avatar
Retired Moderator
Joined: 20 Dec 2010
Last visit: 24 Oct 2013
Posts: 1,095
Own Kudos:
5,167
 [2]
Given Kudos: 376
Posts: 1,095
Kudos: 5,167
 [2]
A certain class consists of 8 students, including Don. Each 01 Mar 2011, 04:47
1
Kudos
Add Kudos
1
Bookmarks
Bookmark this Post
\(\frac{1}{8}*1*1 + \frac{7}{8}*\frac{1}{7}*1+\frac{7}{8}*\frac{6}{7}*\frac{1}{6}\)

\(3*\frac{1}{8} = \frac{3}{8}\)

Ans: "B"
User avatar
Bunuel
User avatar
Math Expert
Joined: 02 Sep 2009
Last visit: 23 Apr 2026
Posts: 109,782
Own Kudos:
810,823
 [4]
Given Kudos: 105,853
Products:
GMAT Club Tests Forum Quiz
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 109,782
Kudos: 810,823
 [4]
A certain class consists of 8 students, including Don. Each 01 Mar 2011, 06:18
3
Kudos
Add Kudos
1
Bookmarks
Bookmark this Post
tirupatibalaji
A certain class consists of 8 students, including Don. Each day, three tasks must be completed and are assigned as follows: one of the 8 students is selected at random to complete Task A, one of the remaining 7 students is selected at random to complete Task B, and one of the remaining six students is selected at random to complete Task C. What is the probability that Don will be selected to complete one of the three tasks?
(A) 1/3
(B) 3/8
(C) 1/24
(D) 1/336
(E) 1/512
Show more

Alternately you can find the probability that among 3 students chosen to complete the tasks won't be Don and subtract it from 1:
\(P=1-\frac{C^3_7}{C^3_8}=\frac{3}{8}\);

The same with probability approach: \(P=1-\frac{7}{8}*\frac{6}{7}*\frac{5}{6}=\frac{3}{8}\).

Answer: B.
User avatar
gmat1220
User avatar
Joined: 03 Feb 2011
Last visit: 17 Feb 2020
Posts: 461
Own Kudos:
1,015
Given Kudos: 123
Status:Impossible is not a fact. It's an opinion. It's a dare. Impossible is nothing.
Affiliations: University of Chicago Booth School of Business
Products:
My Reviews
Posts: 461
Kudos: 1,015
A certain class consists of 8 students, including Don. Each 01 Mar 2011, 06:21
Kudos
Add Kudos
Bookmarks
Bookmark this Post
P(don will not be selected to complete any) = (1 - 1/8) (1 - 1/7) (1 - 1/6) = 5/8

P(don will be selected atleast once) = 1 - 5/8 = 3/8
User avatar
IanStewart
User avatar
GMAT Tutor
Joined: 24 Jun 2008
Last visit: 17 Apr 2026
Posts: 4,143
Own Kudos:
11,271
 [3]
Given Kudos: 99
Expert
Expert reply
Posts: 4,143
Kudos: 11,271
 [3]
A certain class consists of 8 students, including Don. Each 01 Mar 2011, 07:14
3
Kudos
Add Kudos
Bookmarks
Bookmark this Post
There's no need for a complicated solution here. We're selecting 3 people from 8 and we want to know the probability Don is selected. That's just like lining the 8 people up, and asking the probability Don is one of the first 3 people in line. There are 8 spots for Don, 3 of which are among the first three spots, so the probability must be 3/8.

edit - Or to look at it a different way, each of the 8 people is as likely as anyone else to be selected for A, for B, or for C. That is, the probability Don is selected for A is 1/8, for B is also 1/8 and for C is 1/8, so the probability he is selected for one of the three is 1/8 + 1/8 + 1/8 = 3/8.
User avatar
Kinshook
User avatar
Major Poster
Joined: 03 Jun 2019
Last visit: 23 Apr 2026
Posts: 5,986
Own Kudos:
5,858
 [1]
Given Kudos: 163
Location: India
Schools: HBS '26 CBS '26 Wharton '26
GMAT 1: 690 Q50 V34
WE:Engineering (Transportation)
Products:
My Reviews
Schools: HBS '26 CBS '26 Wharton '26
GMAT 1: 690 Q50 V34
Posts: 5,986
Kudos: 5,858
 [1]
A certain class consists of 8 students, including Don. Each 28 Apr 2020, 09:36
Kudos
Add Kudos
1
Bookmarks
Bookmark this Post
tirupatibalaji
A certain class consists of 8 students, including Don. Each day, three tasks must be completed and are assigned as follows: one of the 8 students is selected at random to complete Task A, one of the remaining 7 students is selected at random to complete Task B, and one of the remaining six students is selected at random to complete Task C. What is the probability that Don will be selected to complete one of the three tasks?

A. 1/3
B. 3/8
C. 1/24
D. 1/336
E. 1/512
Show more

Given: A certain class consists of 8 students, including Don. Each day, three tasks must be completed and are assigned as follows: one of the 8 students is selected at random to complete Task A, one of the remaining 7 students is selected at random to complete Task B, and one of the remaining six students is selected at random to complete Task C.

Asked: What is the probability that Don will be selected to complete one of the three tasks?

Total number of ways to assign tasks = 8C1*7C1*6C1 = 8*7*6

Number of ways that Don will be selected to complete one of the three tasks = 7C2 * 3! = 7*6*3

Probability that Don will be selected to complete one of the three tasks = 7*6*3/8*7*6 = 3/8

IMO B
User avatar
JoeKan1234
User avatar
Joined: 27 Aug 2022
Last visit: 23 Dec 2024
Posts: 63
Own Kudos:
45
Given Kudos: 147
Posts: 63
Kudos: 45
A certain class consists of 8 students, including Don. Each 23 Jan 2024, 07:04
Kudos
Add Kudos
Bookmarks
Bookmark this Post
7C2=21

8C3=56

21/56=3/8
User avatar
bumpbot
User avatar
Non-Human User
Joined: 09 Sep 2013
Last visit: 04 Jan 2021
Posts: 38,965
Own Kudos:
1,117
Posts: 38,965
Kudos: 1,117
A certain class consists of 8 students, including Don. Each 25 Feb 2025, 03:31
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:
Bunuel
Math Expert
109782 posts
Krunaal
Tuck School Moderator
853 posts