Suppose that a class contains 15 boys and 30 girls and that

Suppose that a class contains 15 boys and 30 girls, and that 10 students are to be selected at random for a special assignment. Find the probability that exactly 3 boys will be selected. Show how to calculate in excel.

Solution

a)

There are 15C3 ways to select 3 boys, and 30C7 ways to select girls. Thus, there are (15C3)(30C7) ways to do this.

There are 45C10 ways to choose anyone.

Thus, in Excel,

=COMBIN(15,3)*COMBIN(30,7)/COMBIN(45,10)

P = 0.29035568 [ANSWER]