BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

:(

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Legendary Member
Posts: 512
Joined: Mon Jun 18, 2012 11:31 pm
Thanked: 42 times
Followed by:20 members

:(

by sana.noor » Wed Jul 31, 2013 3:17 am
Seven men and seven women have to sit around a circular table so that no 2 women are together. In how many different ways can this be done?
a.24
b.6
c.4
d.12
e.3

i dont know its answer
Work hard in Silence, Let Success make the noise.

If you found my Post really helpful, then don't forget to click the Thank/follow me button. :)
Top
Source: — Problem Solving |
Master | Next Rank: 500 Posts
Posts: 145
Joined: Fri Jan 18, 2013 8:27 am
Thanked: 7 times

by sparkles3144 » Wed Jul 31, 2013 4:55 am
14 places for 14 people

Women cannot sit next to each other. Therefore, it will be MW MW MW MW MW MW MW
Men and women will sit alternatively.

Men = 7!
Women = (7-1)! = 6!
Total = 6!*7!
Top
Senior | Next Rank: 100 Posts
Posts: 32
Joined: Tue Jun 25, 2013 2:56 am
Thanked: 4 times

by luckypiscian » Wed Jul 31, 2013 10:59 pm
As sparkles3144 correctly mentions
"Women cannot sit next to each other. Therefore, it will be MW MW MW MW MW MW MW"

If we forget the circular table for a while
there are 7 seats for men which can be filled in 7! ways
and similarly for women that can be filled in 7! ways
7 seats for men can be chosen in 2 ways
hence total ways = 7! * 7! * 2

now arrange them on a circular table in the same sequence
n. of ways will be
7! * 7! * 2 / 14
since on a circular table ABCDEFGHIJKLMN is same as BCDEFGHIJKLMNA and 12 others (shifting 1 by 1)

= 7! * 6!
Top
Post new topic Post Reply
• Page 1 of 1