Last visit was: 23 Apr 2026, 23:06 It is currently 23 Apr 2026, 23:06
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
MartyTargetTestPrep
User avatar
Target Test Prep Representative
Joined: 24 Nov 2014
Last visit: 11 Aug 2023
Posts: 3,472
Own Kudos:
5,641
 [4]
Given Kudos: 1,430
Status:Chief Curriculum and Content Architect
Affiliations: Target Test Prep
GMAT 1: 800 Q51 V51
Expert
Expert reply
GMAT 1: 800 Q51 V51
Posts: 3,472
Kudos: 5,641
 [4]
How many different ways can you select a pilot and a co pilot if you 01 Apr 2016, 23:16
1
Kudos
Add Kudos
3
Bookmarks
Bookmark this Post
00:00
Start Timer
Pause Timer
Resume Timer
Show Answer
Hide
Show
History
E
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!

Difficulty:

25% (medium)

Question Stats:

66% (00:43) correct 34% (00:56) wrong based on 153 sessions

History

Date
Time
Result
Not Attempted Yet
How many different ways can you select a pilot and a co pilot if you have 100 people to choose from?

(A) 199
(B) 200
(C) 398
(D) 4950
(E) 9900


Source: Marty Murray
ShowHide Answer
Official Answer
E
User avatar
chetan2u
User avatar
GMAT Expert
Joined: 02 Aug 2009
Last visit: 22 Apr 2026
Posts: 11,229
Own Kudos:
45,005
 [2]
Given Kudos: 335
Status:Math and DI Expert
Location: India
Concentration: Human Resources, General Management
GMAT Focus 1: 735 Q90 V89 DI81
Products:
My Reviews
Expert
Expert reply
GMAT Focus 1: 735 Q90 V89 DI81
Posts: 11,229
Kudos: 45,005
 [2]
How many different ways can you select a pilot and a co pilot if you 01 Apr 2016, 23:52
1
Kudos
Add Kudos
1
Bookmarks
Bookmark this Post
MartyMurray
How many different ways can you select a pilot and a co pilot if you have 100 people to choose from?

(A) 199
(B) 200
(C) 398
(D) 4950
(E) 9900


Source: Marty Murray
Show more

Different ways/approach to do the Q, although the concept/logic is same..



1) PERMUTATION:-
since it is selection, we have to find permutation..
100P2= 100!/(100-2)!=100*99=9900

2) COMBINATION:-
the ways to select 2 for 2 posts= 100C2
=> 100!/2!98! = 4950
But these 2 can be arranged in 2! ways..
Total= 4950*2! = 9900

3) choose for each post
First post say PILOT can be filled with any of the 100..
co-pilot can be filled by any of the remaining 99
Total = 100*99=9900..

E
User avatar
KS15
User avatar
Joined: 21 May 2013
Last visit: 25 Jul 2019
Posts: 531
Own Kudos:
259
Given Kudos: 608
Posts: 531
Kudos: 259
How many different ways can you select a pilot and a co pilot if you 03 Apr 2016, 09:12
Kudos
Add Kudos
Bookmarks
Bookmark this Post
MartyMurray
How many different ways can you select a pilot and a co pilot if you have 100 people to choose from?

(A) 199
(B) 200
(C) 398
(D) 4950
(E) 9900


Source: Marty Murray
Show more


I feel the answer should be D as we are only talking about selection here i.e 100c2
User avatar
MartyTargetTestPrep
User avatar
Target Test Prep Representative
Joined: 24 Nov 2014
Last visit: 11 Aug 2023
Posts: 3,472
Own Kudos:
5,641
Given Kudos: 1,430
Status:Chief Curriculum and Content Architect
Affiliations: Target Test Prep
GMAT 1: 800 Q51 V51
Expert
Expert reply
GMAT 1: 800 Q51 V51
Posts: 3,472
Kudos: 5,641
How many different ways can you select a pilot and a co pilot if you 03 Apr 2016, 15:21
Kudos
Add Kudos
Bookmarks
Bookmark this Post
KS15
I feel the answer should be D as we are only talking about selection here i.e 100c2
Show more

What you said would be correct except that the question has an additional level to it.

You are not just choosing two from 100. Each of the two people chosen fills a particular slot. The first filling the pilot slot and the second filling the copilot slot is different from the first filling the copilot slot and the second filling the pilot slot.

So the answer is in a sense (100C2) x 2 = 9900.
User avatar
KS15
User avatar
Joined: 21 May 2013
Last visit: 25 Jul 2019
Posts: 531
Own Kudos:
259
Given Kudos: 608
Posts: 531
Kudos: 259
How many different ways can you select a pilot and a co pilot if you 03 Apr 2016, 20:53
Kudos
Add Kudos
Bookmarks
Bookmark this Post
MartyMurray
KS15
I feel the answer should be D as we are only talking about selection here i.e 100c2

What you said would be correct except that the question has an additional level to it.

You are not just choosing two from 100. Each of the two people chosen fills a particular slot. The first filling the pilot slot and the second filling the copilot slot is different from the first filling the copilot slot and the second filling the pilot slot.

So the answer is in a sense (100C2) x 2 = 9900.
Show more


But that should be come as part of arrangement correct-which is not part of the question

Thanks,
Karthik
User avatar
MartyTargetTestPrep
User avatar
Target Test Prep Representative
Joined: 24 Nov 2014
Last visit: 11 Aug 2023
Posts: 3,472
Own Kudos:
5,641
Given Kudos: 1,430
Status:Chief Curriculum and Content Architect
Affiliations: Target Test Prep
GMAT 1: 800 Q51 V51
Expert
Expert reply
GMAT 1: 800 Q51 V51
Posts: 3,472
Kudos: 5,641
How many different ways can you select a pilot and a co pilot if you 03 Apr 2016, 21:05
Kudos
Add Kudos
Bookmarks
Bookmark this Post
KS15
MartyMurray
KS15
I feel the answer should be D as we are only talking about selection here i.e 100c2

What you said would be correct except that the question has an additional level to it.

You are not just choosing two from 100. Each of the two people chosen fills a particular slot. The first filling the pilot slot and the second filling the copilot slot is different from the first filling the copilot slot and the second filling the pilot slot.

So the answer is in a sense (100C2) x 2 = 9900.


But that should be come as part of arrangement correct-which is not part of the question

Thanks,
Karthik
Show more

It absolutely is part of the question. The question makes clear that there are two different slots to fill, rather than just two undifferentiated positions. So for every two people chosen there are two possible arrangements.
User avatar
bumpbot
User avatar
Non-Human User
Joined: 09 Sep 2013
Last visit: 04 Jan 2021
Posts: 38,963
Own Kudos:
1,117
Posts: 38,963
Kudos: 1,117
How many different ways can you select a pilot and a co pilot if you 20 Nov 2018, 22:28
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
109802 posts
Krunaal
Tuck School Moderator
853 posts