Question

In a group of 20 students, 7 study both Art and Biology.

5 study Biology but not Art.
8 study neither subject.
Given that a randomly selected student studies Art, what is the probability the student studies Art and Biology?​

Answer 1

Explanation:

A + B = 7

(Not A) + B = 5

(Not A) + (Not B) = 8

(Not A) = ((Not A) + B) + ((Not A) + (Not B) = 13

A = 20 - (Not A) = 7

Prob (A + B) given (A)

Prob (A+B) || A = (7/20) / (7/20)

Prob (A + B) || A = 1