Question

Suppose that 20° of boys opted for mathematics and 40% of girls opted for mathematics. What is the probability that a student opted for mathematics if half of the class is girls?​

Answer 1

30% Chance

Explanation:

This one is rather simple. If half the class is girls, split 40 into half. Do the same with 20 if half is boys. Add 10 and 20 and you get 30.

Answer 2

Answer: 30%

Explanation:

Let A be the probability of a student opting for mathematics - it consists of either boy opting for mathematics or girl opting for mathematics. As there is "or" we need to sum these probabilities.

`P(A) = P(B)* P(M|G) + P(G)*P(M|G)`

`P(A) = (1)/(2) * (20)/(100) + (1)/(2) * (40)/(100)`

`P(A) = 3/10 = 0.3`

=> 30%