Problem Solving

Rahul@gurome wrote:

aarati wrote:9 balls are to be placed in 9 boxes and 5 of the balls cannot fit into 3 small boxes. The number of ways of

arranging one ball in each of the boxes is

(a) 18720
(b)18270
(c)17280
(d)12780
help me to solve it......

No. of ways 5 balls can be placed in 6 boxes (except 3 small boxes) = 6P5 = 6!/(6-5)! = 6*5*4*3*2 = 720 ways
Remaining balls = 4
No. of ways 4 balls can be placed in 3 small boxes = 4P3 = 4!/(4-3)! = 4*3*2 = 24 ways
Number of ways of arranging one ball in each of the boxes = 720 * 24 = 17,280

The correct answer is (C).