A medical research group plans to select 2 volunteers out of 8 for a drug experiment. In how many ways can they choose the 2 volunteers?

Answer:They can choose the 2 volunteers in 28 different waysStep-by-step explanation:Well, as the research group has to choose 2 volunteers out of 8, this means that it doesn't matter the order in which they choose them as long as they are two.In statistics this is considered a counting technique and is called combination.The combination formula is:[tex]C(n,r)=\frac{n!}{r!(n-r)!}[/tex]where[tex]n[/tex] is the set of elementsand [tex]r[/tex] is the number of elements taken from nThen [tex]n=8[/tex] and [tex]r= 2[/tex]We replace in the combination formula:[tex]C(8,2)=\frac{8!}{2!(8-2)!}[/tex][tex]C(8,2)=\frac{8!}{2!(6!)}[/tex][tex]C(8,2)=\frac{40320}{2(720)}[/tex][tex]C(8,2)=\frac{40320}{1440}[/tex][tex]C(8,2)=28}[/tex]This result means that Medical research group can choose the 2 volunteers in 28 different ways