Finding the number of objects in permutation

Question

What is n in this permutation, P(n, 3) = 60?

Please help me solve this.

Could you add a little more detail? For example, what is the definition of $P(n,3)$? — Micapps, Jan 07 '16 at 12:52

score 2 · Accepted Answer · answered Jan 07 '16 at 12:54

2

Its easy $\frac{n!}{(n-3)!}=60$ so $(n)(n-1)(n-2)=60$ we need to find three consecutive numbers whose product is $60$ so it can be easily seen that $5.4.3$ satisfy it thus $n=5$ .to cross check see $P(5,3)$

answered Jan 07 '16 at 12:54

Archis Welankar

15,910

Thanks a lot for your help – Stephen Mark Jan 07 '16 at 13:04
Your welcome!!.. – Archis Welankar Jan 07 '16 at 13:09
But how about r is missing? What's the process? I really have a hard time with statistics hehehe – Stephen Mark Jan 07 '16 at 13:11
$r=3$ so it isnt missing – Archis Welankar Jan 07 '16 at 13:16

Finding the number of objects in permutation

1 Answers1