Question

in a class 40% of students study mathematics 25% study chemistry 15% both mathematics and chemistry is a student is chosen at random the probability that he studies chemistry

Answer 1

n(S)=40

event A : student study mathematics

A {25% mathematics}

n(A)=25

p(A) = n(A)/n(S)

=25/40

event B : student study chemistry

B {15% chemistry}

n(B)=15

p(B)=n(B)/n(S)
=15/40