Question

If nPr= 360, find the values of n and r.

Answer 1

n

P

r

=

(n−r)!

n!

=360-- (1)

n

C

r

=

(r!)(n−r)!

n!

=15 -- (2)

Dividing eqn 1 by 2, we get

=>r!=

15

360

=24

=>r!=4×2×3×1=4!

So, r=4