Given a group of n object. We want to make a selection of k objects out of the n object. This can be done in
C(n, k) many ways, where [tex]C(n, k)= \frac{n!}{k!(n-k)!} [/tex],
where k!=1*2*3*...(k-1)*k
Thus, we can do the selection of 3 cd's out of 5, in C(5,3) many ways,
where
[tex]C(5, 3)= \frac{5!}{3!2!}= \frac{5*4*3*2*1}{3*2*1*2*1}= \frac{5*4}{2}=10 [/tex]
Answer: 10
