Suppose a survey of 20 students was taken as they walked out of the cafeteria with regards to their age. The results are listed in the table:

Question

Q12. Suppose a survey of 20 students was taken as they walked out of the cafeteria with regards to their age. The results are listed in the table:

	Older than 30	30 or younger
Male	3	9
Female	2	6

Suppose one person surveyed is selected at random. Find the probability that:

(a)  A male and someone older than 30 was selected

(b)  A female or someone 30 or younger was selected

(c)  Someone older than 30 was selected, given they were female.

Answer 1

	Older than 30	30 or younger
Male	3	9 12
Female	2	6 8

5 15 20

(a)  A male and someone older than 30 was selected: 3/20

(b)  A female or someone 30 or younger was selected

female (8/20) + 30 or younger (15/20) - female & 30 or younger (6/20) = 17/20

(c)  Someone older than 30 was selected, given they were female: 2/8 = 1/4