Solve the problem.
-Mary finds 9 fish at a pet store that she would like to buy, but she can afford only 5 of them. In how many ways can she make her selection? How many ways can she make her selection if he decides that one of the fish is a must?
A)3024; 1680
B)7560; 840
C)126; 70
D)15,120; 1680

Question

Quizplus · Accepted Answer

Mary can select 5 fish out of 9 in $ \binom{9}{5} = 126 $ ways. If one fish is a must, then she needs to choose 4 out of the remaining 8, which can be done in $ \binom{8}{4} = 70 $ ways.

Solve the Problem. -Mary Finds 9 Fish at a Pet Store That She