Question

If 6Pr = 360 and If 6Cr = 15, find r ?
A.5
B.6
C.4
D.3

Answer 1

6Pr = 6!/(6-r)! = 360

6Cr = 6! / r! ( 6 -r)! = 15

r! ( 6- r)! / 6!= 1/15
6! / ( 6-r)! = 360

Multiply

r! = 24

r = 4