Question

A group of 8 members is to be selected from a 16 teachers
and 24 students.

Find:
a) The probability that the group has exactly 4 students

b) The probability that the group has at least 2 students

Answer 1

exactly 4 students --- 4 students from 24 and then 4 teachers from 16
= C(24,4)*C(16,4)
= 10626*1820 = ....

at least 2 students
= all cases - (exactly no student + exactly 1 student)
= C( 40,8) - C(16,8)*C(24,0) - C(16,7)*C(24,1)
= ....