Question

A class consists of 35 girls and 45 boys,9 girls and 17 boys of the class take mathematics as their optional subject what is the probability that a student selected at random from the class is a boy or takes mathematics?

Answer 1

The table given below ,

	Takes Mathematics	Does not Takes Mathematics	Total
Boys	17	28	45
Girls	9	26	35
Total	26	54	80

Let , A be the event that the student is a boy and B be the event that the students takes Mathematics as their optional subject.

Also , let , be the event that the students is boy and he takes Mathematics as their optional subject.

Now , given that n(A)=45 , n(B)=26 ,

Therefore ,

Therefore , by using addition rule ,

Therefore , the probability that a student selected at random from the class is a boy or takes mathematics is 0.6750