Two teachers are chosen randomly from a staff consisting 3 women and 2 men to attend a HIV/AIDS seminar. Calculate the probability that the two teachers chosen are:

(a) Of the same sex
(b) Of opposite sex

1 answer

either 2 men or 2 women.
with no restriction:
number of choices = C(5,2) = 10

number choices of 2 women = C(2,2) = 1
number of choices of 2 men = C(3,2) = 3

prob of 2 of same sex = 4/10 = 2/5

prob of 2 of opposite sex = 1 - 2/5 = 3/5