Find all School-related info fast with the new School-Specific MBA Forum

 It is currently 26 Apr 2015, 22:05

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

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

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

A committee of 3 has to be formed randomly from a group of 6

Author Message
TAGS:
Intern
Joined: 14 Jul 2006
Posts: 6
Followers: 0

Kudos [?]: 0 [0], given: 0

A committee of 3 has to be formed randomly from a group of 6 [#permalink]  23 Aug 2007, 18:48
A committee of 3 has to be formed randomly from a group of 6 people. Tom and Mary are in this group of 6. What is the probability that Tom will be selected into the committee but Mary will not?

1/10
1/5
3/10
2/5
1/2

This question is a lot easier than I made it out to be. What do you see in the question that tips you off to the easiest method to solve? I keep confusing something in these types of probability questions. Thanks for the help!
Manager
Joined: 03 Sep 2006
Posts: 233
Followers: 1

Kudos [?]: 5 [0], given: 0

Brrr - I got 1/10

1st person - Tom: 1/6
2nd person - not Mary 4/5
3rd person - not Mary - 3/4

P = 1/6 * 4/5 * 3/4 = 1/10

P.S> If Tom is 2nd or 3rd - there are no such answers for this probability in the answer choices
Senior Manager
Joined: 13 May 2007
Posts: 252
Followers: 2

Kudos [?]: 7 [0], given: 0

total committees : 6c3 = 20

committees with only tom = 6

ans : 6/20 = 3/10
Manager
Joined: 08 Oct 2006
Posts: 215
Followers: 1

Kudos [?]: 5 [0], given: 0

3/10 it is.
Total committes posssible = 6C3
Committee with Tom= 4C2=6

Thus 6/20= 3/10
Manager
Joined: 03 Sep 2006
Posts: 233
Followers: 1

Kudos [?]: 5 [0], given: 0

empty_spaces or excelgmat,
could you please explain why Committee with Tom = 6?
Senior Manager
Joined: 13 May 2007
Posts: 252
Followers: 2

Kudos [?]: 7 [0], given: 0

Whatever wrote:
empty_spaces or excelgmat,
could you please explain why Committee with Tom = 6?

you want tom and 2 other people
2 others from a pool of 4 can be chosen in 4c2 ways = 6
Manager
Joined: 03 Sep 2006
Posts: 233
Followers: 1

Kudos [?]: 5 [0], given: 0

empty_spaces wrote:
you want tom and 2 other people
2 others from a pool of 4 can be chosen in 4c2 ways = 6

Ic, thanks. I forgot to exclude Mary to get 4 people =)
Similar topics Replies Last post
Similar
Topics:
A committee of 3 has to be formed randomly from a group of 6 people 0 29 Jan 2015, 07:29
A committee of 3 has to be formed randomly from a group of 6 0 06 Jan 2013, 12:09
10 Ben needs to form a committee of 3 from a group of 8 enginee 5 15 Jan 2011, 16:28
16 A committee of 3 has to be formed randomly from a group of 6 18 18 Jul 2009, 13:03
A committee of 3 has to be formed out of 6 people. John and 8 02 Jun 2005, 08:04
Display posts from previous: Sort by