By 32,760 different ways can a researcher select 4 rats from 15 rats and assign each to a different test .
Step-by-step explanation:
We need to find How many different ways can a researcher select 4 rats from 15 rats and assign each to a different test.Let's find out:
We will use Permutation here : As we will chose 4 rats out of 15 rats , order will be considered which will make this as a permutation problem . Formula for permutation is given by :
⇒ [tex]nP_r= \frac{n!}{(n-r)!}[/tex]
According to question , we have
⇒ [tex]15P_4= \frac{15!}{(15-4)!}[/tex]
⇒ [tex]15P_4= \frac{15!}{(11)!}[/tex]
⇒ [tex]15P_4= \frac{15(14)(13)(12)11!}{(11)!}[/tex]
⇒ [tex]15P_4= 15(14)(13)(12)[/tex]
⇒ [tex]15P_4= 32,760[/tex]
Therefore , By 32,760 different ways can a researcher select 4 rats from 15 rats and assign each to a different test .
