Question

if nP3:nP4 =1:9,find n

Answer 1

Answer:

n = 12

Step-by-step explanation:

$np_{r} = \frac{n!}{n-r!}$

$np_{3}:np_{4} = \frac{n!}{n-3!}:\frac{n!}{n-4!}$

= $\frac{1}{n-3}:\frac{1}{1}$

= $1:n-3 = 1:9$

$=> n-3 = 9 => n= 12$