
Permutation and Combination  Quant/Math  CAT 2013
Question 4 the day:
August 20, 2003
The question for the day is from the topic of Permutation and Combination.
 In how many ways can 15 people be seated around two round tables with seating capacities of 7 and 8 people?
(1) 
15!/(8!) 
 
(2) 
7!*8! 
(3) 
(15C8)*6!*7! 
 
(4) 
2*(15C7)*6!*7! 
Correct Answer  (3)
Solution:
You can choose the 7 people to sit in the first table in ^{15}C_{7} ways. After selecting 7 people for the table that can seat 7 people, they can be seated in (71)! = 6!.
The remaining 8 people can be made to sit around the circular table in (81)! = 7! Ways.
Hence, total number of ways ^{15}C_{8} * 6! * 7!



