NEW HERE? LEARN MORE
closeclose
Last visit was: 23 Apr 2024, 10:09 It is currently 23 Apr 2024, 10:09
Decision Tracker
My Rewards
New posts
New comers' posts

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

A city council will select 2 of 9 available firefighters and

SORT BY:
Date
Kudos
Tags:
Find Similar Topics 
Show Tags
Hide Tags
User avatar
macjas
Senior Manager
Senior Manager
Joined: 09 May 2012
Affiliations: UWC
Posts: 314
Own Kudos [?]: 8796 [9]
Given Kudos: 100
Location: Canada
Schools: Rotman '15 (A) Schulich '15 (M)
GMAT 1: 620 Q42 V33
GMAT 2: 680 Q44 V38
GPA: 3.43
WE:Engineering (Entertainment and Sports)
Send PM
Reviews Badge
A city council will select 2 of 9 available firefighters and [#permalink] New post   27 May 2012, 09:08
5
Kudos
4
Bookmarks
00:00
A
B
C
D
E

Difficulty:

5% (low)

Question Stats:

80% (01:01) correct 20% (01:34) wrong based on 214 sessions
Hide Show timer Statistics
A city council will select 2 of 9 available firefighters and 1 of 6 available police officers to serve on an advisory panel. How many different groups of 3 could serve on the panel?

A. 36
B. 72
C. 144
D. 216
E. 432
ShowHide Answer
Official Answer
D
Most Helpful Reply
User avatar
L
Bunuel
Math Expert
Joined: 02 Sep 2009
Posts: 92875
Own Kudos [?]: 618547 [5]
Given Kudos: 81561
Send PM
CAT Tests Forum Quiz Mode
Re: A city council will select 2 of 9 available firefighters and [#permalink] New post   28 May 2012, 02:04
4
Kudos
1
Bookmarks
Expert Reply
macjas wrote:
A city council will select 2 of 9 available firefighters and 1 of 6 available police officers to serve on an advisory panel. How many different groups of 3 could serve on the panel?

A. 36
B. 72
C. 144
D. 216
E. 432


Ways to select 2 firefighters out of 9 is \(C^2_9=36\);
Ways to select 1 police officer out of 6 is \(C^1_6=6\);

Total ways to select 2 firefighters out of 9 and 1 police officer out of 6 is 36*6=216.

It's called Principle of Multiplication: if one event can occur in m ways and a second can occur independently of the first in n ways, then the two events can occur in m*n ways.

Answer: D.
General Discussion
avatar
ankitbansal85
Intern
Intern
Joined: 01 Apr 2012
Posts: 24
Own Kudos [?]: 17 [0]
Given Kudos: 18
Location: United States
Concentration: Technology, Economics
GMAT Date: 05-13-2012
WE:Consulting (Computer Software)
Send PM
Re: A city council will select 2 of 9 available firefighters a [#permalink] New post   27 May 2012, 23:39
OA D

9C2 * 6C1

using the combination formula to choose 2 from 9 and 1 from 6
User avatar
Skag55
Manager
Manager
Joined: 26 Feb 2013
Posts: 124
Own Kudos [?]: 180 [0]
Given Kudos: 25
Send PM
Re: A city council will select 2 of 9 available firefighters and [#permalink] New post   08 Sep 2013, 00:09
The "how many different groups of 3" threw me at first, I thought I needed to exclude something, or say something like "we got 15 in total, so 5 groups of 3..." and so some calculations there.

Can someone please explain to me, in which case we would have divided the product of the two combinations by the total people selected out of the population? i.e. 15C5
User avatar
L
Bunuel
Math Expert
Joined: 02 Sep 2009
Posts: 92875
Own Kudos [?]: 618547 [0]
Given Kudos: 81561
Send PM
CAT Tests Forum Quiz Mode
Re: A city council will select 2 of 9 available firefighters and [#permalink] New post   08 Sep 2013, 05:00
Expert Reply
Skag55 wrote:
The "how many different groups of 3" threw me at first, I thought I needed to exclude something, or say something like "we got 15 in total, so 5 groups of 3..." and so some calculations there.

Can someone please explain to me, in which case we would have divided the product of the two combinations by the total people selected out of the population? i.e. 15C5


We would divide by 15C3 if the question were: what is the probability that when we select 3 people out of 9 firefighters and 6 police officers we get 2 firefighters and 1 police officer.
User avatar
Skag55
Manager
Manager
Joined: 26 Feb 2013
Posts: 124
Own Kudos [?]: 180 [0]
Given Kudos: 25
Send PM
Re: A city council will select 2 of 9 available firefighters and [#permalink] New post   08 Sep 2013, 10:30
Great, many thanks!
User avatar
L
ScottTargetTestPrep
Target Test Prep Representative
Joined: 14 Oct 2015
Status:Founder & CEO
Affiliations: Target Test Prep
Posts: 18745
Own Kudos [?]: 22038 [0]
Given Kudos: 283
Location: United States (CA)
Send PM
Re: A city council will select 2 of 9 available firefighters and [#permalink] New post   11 Mar 2019, 08:15
Expert Reply
macjas wrote:
A city council will select 2 of 9 available firefighters and 1 of 6 available police officers to serve on an advisory panel. How many different groups of 3 could serve on the panel?

A. 36
B. 72
C. 144
D. 216
E. 432


The number of ways to select the firefighters is 9C2 = 9!/(2! x 7!) = (9 x 8)/2! = 36.

The number of ways to select the police officers is 6C1 = 6s.

The total number of ways to select the group is 36 x 6 = 216.

Answer: D
User avatar
bumpbot
Non-Human User
Joined: 09 Sep 2013
Posts: 32623
Own Kudos [?]: 821 [0]
Given Kudos: 0
Send PM
Re: A city council will select 2 of 9 available firefighters and [#permalink] New post   23 Jun 2021, 03:01
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
GMAT Club Bot
gmatclubot
Re: A city council will select 2 of 9 available firefighters and [#permalink]
23 Jun 2021, 03:01
Moderators:
Bunuel
Math Expert
92875 posts
yashikaaggarwal
Senior Moderator - Masters Forum
3137 posts

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne
Main navigation
GMAT Resources
Partners
MBA Resources
www.gmac.com|www.mba.com | | GMAT Club Rules | Terms and Conditions