Last visit was: 23 Apr 2026, 05:07 It is currently 23 Apr 2026, 05:07
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
MathRevolution
User avatar
Math Revolution GMAT Instructor
Joined: 16 Aug 2015
Last visit: 27 Sep 2022
Posts: 10,063
Own Kudos:
20,000
 [3]
Given Kudos: 4
GMAT 1: 760 Q51 V42
GPA: 3.82
Expert
Expert reply
GMAT 1: 760 Q51 V42
Posts: 10,063
Kudos: 20,000
 [3]
How many possible cases are there such that 2 stocks are selected at r 07 Apr 2016, 06:08
Kudos
Add Kudos
3
Bookmarks
Bookmark this Post
00:00
Start Timer
Pause Timer
Resume Timer
Show Answer
Hide
Show
History
C
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!

Difficulty:

5% (low)

Question Stats:

98% (00:27) correct 2% (00:03) wrong based on 130 sessions

History

Date
Time
Result
Not Attempted Yet
How many possible cases are there such that 2 stocks are selected at random from 10 stocks?

A. 35
B. 40
C. 45
D. 50
E. 55


* A solution will be posted in two days.
ShowHide Answer
Official Answer
C
User avatar
chetan2u
User avatar
GMAT Expert
Joined: 02 Aug 2009
Last visit: 22 Apr 2026
Posts: 11,229
Own Kudos:
44,999
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: 44,999
How many possible cases are there such that 2 stocks are selected at r 07 Apr 2016, 22:19
Kudos
Add Kudos
Bookmarks
Bookmark this Post
MathRevolution
How many possible cases are there such that 2 stocks are selected at random from 10 stocks?

A. 35
B. 40
C. 45
D. 50
E. 55


* A solution will be posted in two days.
Show more

Hi,
the Q is of COMBINATIONS but marked as PROBABILITY..
Please change it..
User avatar
Bunuel
User avatar
Math Expert
Joined: 02 Sep 2009
Last visit: 23 Apr 2026
Posts: 109,776
Own Kudos:
810,757
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: 109,776
Kudos: 810,757
How many possible cases are there such that 2 stocks are selected at r 07 Apr 2016, 22:43
Kudos
Add Kudos
Bookmarks
Bookmark this Post
chetan2u
MathRevolution
How many possible cases are there such that 2 stocks are selected at random from 10 stocks?

A. 35
B. 40
C. 45
D. 50
E. 55


* A solution will be posted in two days.

Hi,
the Q is of COMBINATIONS but marked as PROBABILITY..
Please change it..
Show more

Edited the tag. Thank you.
User avatar
Skywalker18
User avatar
Retired Moderator
Joined: 08 Dec 2013
Last visit: 15 Nov 2023
Posts: 1,973
Own Kudos:
10,162
Given Kudos: 171
Status:Greatness begins beyond your comfort zone
Location: India
Concentration: General Management, Strategy
GPA: 3.2
WE:Information Technology (Consulting)
Products:
My Reviews
Posts: 1,973
Kudos: 10,162
How many possible cases are there such that 2 stocks are selected at r 07 Apr 2016, 23:32
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Number of possible cases = 10c2
=10!/(8!*2!)
=10*9/2
=45
Answer C
User avatar
GMATinsight
User avatar
Major Poster
Joined: 08 Jul 2010
Last visit: 23 Apr 2026
Posts: 6,976
Own Kudos:
16,905
Given Kudos: 128
Status:GMAT/GRE Tutor l Admission Consultant l On-Demand Course creator
Location: India
GMAT: QUANT+DI EXPERT
Schools: IIM (A) ISB '24
GMAT 1: 750 Q51 V41
WE:Education (Education)
Products:
My Reviews
Expert
Expert reply
Schools: IIM (A) ISB '24
GMAT 1: 750 Q51 V41
Posts: 6,976
Kudos: 16,905
How many possible cases are there such that 2 stocks are selected at r 12 Apr 2016, 07:53
Kudos
Add Kudos
Bookmarks
Bookmark this Post
chetan2u
MathRevolution
How many possible cases are there such that 2 stocks are selected at random from 10 stocks?

A. 35
B. 40
C. 45
D. 50
E. 55


* A solution will be posted in two days.

Hi,
the Q is of COMBINATIONS but marked as PROBABILITY..
Please change it..
Show more

Method 1:
No. of ways of selecting two out of 10 stocks = 10C2 = 10!/(2!*8!) = 45

Method 2:
No. of ways of making pair of one stock with each of the remaining stock = 9
Total Such possible pairs (with Repetition) = 10*9 = 90
Since every case has been counted twice therefore total Unique pairs = 10*9 / 2 = 45

Method 3:
Pairs of first stock with each of the 9 stocks can be made in 9 ways

Pairs of Second stock with each of the remaining 8 stocks can be made in 8 ways (second has already made pair
with first so we will not make that pair again

Pairs of Third stock with each of the remaining 7 stocks can be made in 7 ways (Third has already made pair with first and second so we will not make those pairs again) .... and so on...

Total Such pairs = 9+8+7+6+5+4+3+2+1 = 45

Answer: option C
User avatar
MathRevolution
User avatar
Math Revolution GMAT Instructor
Joined: 16 Aug 2015
Last visit: 27 Sep 2022
Posts: 10,063
Own Kudos:
20,000
Given Kudos: 4
GMAT 1: 760 Q51 V42
GPA: 3.82
Expert
Expert reply
GMAT 1: 760 Q51 V42
Posts: 10,063
Kudos: 20,000
How many possible cases are there such that 2 stocks are selected at r 19 Apr 2016, 05:58
Kudos
Add Kudos
Bookmarks
Bookmark this Post
How many possible cases are there such that 2 stocks are selected at random from 10 stocks?

A. 35
B. 40
C. 45
D. 50
E. 55

->10C2=10*9/2*1=45. Thus, the answer is C.
avatar
robu
avatar
Joined: 03 Dec 2014
Last visit: 16 Mar 2017
Posts: 69
Own Kudos:
181
Given Kudos: 391
Location: India
Concentration: General Management, Leadership
Schools: IIMA ISB '17 INSEAD Jan '17
GMAT 1: 620 Q48 V27
GPA: 1.9
WE:Engineering (Energy)
Schools: IIMA ISB '17 INSEAD Jan '17
GMAT 1: 620 Q48 V27
Posts: 69
Kudos: 181
How many possible cases are there such that 2 stocks are selected at r 19 Apr 2016, 09:38
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Bunuel
chetan2u
MathRevolution
How many possible cases are there such that 2 stocks are selected at random from 10 stocks?

A. 35
B. 40
C. 45
D. 50
E. 55


* A solution will be posted in two days.

Hi,
the Q is of COMBINATIONS but marked as PROBABILITY..
Please change it..

Edited the tag. Thank you.
Show more




sir what is the difference between random and simultaneously. can we use 10c1x9c1 in random case? please explain
User avatar
bumpbot
User avatar
Non-Human User
Joined: 09 Sep 2013
Last visit: 04 Jan 2021
Posts: 38,957
Own Kudos:
1,117
Posts: 38,957
Kudos: 1,117
How many possible cases are there such that 2 stocks are selected at r 01 Jul 2017, 08:21
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
109776 posts
Krunaal
Tuck School Moderator
853 posts