Eurovision permutations (650+)

This topic has expert replies
Legendary Member
Posts: 1337
Joined: Sat Dec 27, 2008 6:29 pm
Thanked: 127 times
Followed by:10 members

Eurovision permutations (650+)

by Night reader » Sat Dec 04, 2010 8:15 pm
Mark is a hotel administrator, and he is making room reservations for five participants of the Eurovision song contest. The number of rooms available for the participants is five on the fifth-room floor; the contest manager requires Mark to accommodate all participants so that no male participant's room neighbors other male participant's one. In how many ways can Mark arrange five rooms among three male and two female participants?

A. 24
B. 16
C. 12
D. 48
E. 30
Source: — Problem Solving |

Master | Next Rank: 500 Posts
Posts: 437
Joined: Sat Nov 22, 2008 5:06 am
Location: India
Thanked: 50 times
Followed by:1 members
GMAT Score:580

by beat_gmat_09 » Sat Dec 04, 2010 8:22 pm
Night reader wrote:Mark is a hotel administrator, and he is making room reservations for five participants of the Eurovision song contest. The number of rooms available for the participants is five on the fifth-room floor; the contest manager requires Mark to accommodate all participants so that no male participant's room neighbors other male participant's one. In how many ways can Mark arrange five rooms among three male and two female participants?

A. 24
B. 16
C. 12
D. 48
E. 30
Question asks how many ways to arrange - MFMFM
No. of ways - 3*2*2*1*1 = 12
Hope is the dream of a man awake

Legendary Member
Posts: 1337
Joined: Sat Dec 27, 2008 6:29 pm
Thanked: 127 times
Followed by:10 members

by Night reader » Sat Dec 04, 2010 8:25 pm
Viva!

correct answer C.
thanks

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 1179
Joined: Sun Apr 11, 2010 9:07 pm
Location: Milpitas, CA
Thanked: 447 times
Followed by:88 members

by Rahul@gurome » Sat Dec 04, 2010 8:27 pm
This means that if the rooms are numbered 1 to 5, the males will occupy first, third and fifth rooms and the females will occupy second or fourth rooms.
The number of ways this can be done is 3!*2! = 12.
The correct answer is C.
Rahul Lakhani
Quant Expert
Gurome, Inc.
https://www.GuroMe.com
On MBA sabbatical (at ISB) for 2011-12 - will stay active as time permits
1-800-566-4043 (USA)
+91-99201 32411 (India)

Legendary Member
Posts: 1337
Joined: Sat Dec 27, 2008 6:29 pm
Thanked: 127 times
Followed by:10 members

by Night reader » Sat Dec 04, 2010 8:28 pm
Rahul@gurome wrote:This means that if the rooms are numbered 1 to 5, the males will occupy first, third and fifth rooms and the females will occupy second or fourth rooms.
The number of ways this can be done is 3!*2! = 12.
The correct answer is C.
Rahul, I found it more useful to work with diagrams for permutations rather going through combining and separating events:

___.....___.....___.....___.....___......___
F(3).....M(2).....F(2)....M(1)....F(1).....M(1)

3*2*2*1*1*1=12

User avatar
Legendary Member
Posts: 866
Joined: Mon Aug 02, 2010 6:46 pm
Location: Gwalior, India
Thanked: 31 times

by goyalsau » Sun Dec 05, 2010 2:02 am
Night reader wrote:
no male participant's room neighbors other male participant's one.
There was a time when its said No female participant will neighbor Male Participant, But Now everything is changed, POOR GIRLS........ :D
Saurabh Goyal
[email protected]
-------------------------


EveryBody Wants to Win But Nobody wants to prepare for Win.