Question

In Class XI of a school 40% of the students study Mathematics and 30% study Biology. 10% of the class study both Mathematics and Biology. If a student is selected at random from the class, find the probability that he will be studying Mathematics or Biology.

Answer 1

Let, Abe the event that selected student studies Mathematics and B be the event that selected student studies Biology.

According to given information,

P( A )=40% = 40 100 = 2 5

P( B )=30% = 30 100 = 3 10

P( A and B )=10% = 10 100 = 1 10

The probability that the selected student study Mathematics or Biology P( A or B ) is,

P( A or B )= 2 5 + 3 10 − 1 10 = 6 10 =0.6

Thus, probability that the selected student study Mathematics or Biology is 0.6.