Question

In a class of 20 students, 5 have a brother and 11 have a sister. There are 3 students who have a brother and a sister. What is the probability that a student who does not have a brother has a sister?

attempt 1 out of 2

Answer 1

45%

Explanation:

In a class of 20 students, 5 have a brother and 11 have a sister. There are 3 students who have a brother and a sister. What is the probability that a student who does not have a brother has a sister?

P (no bro / yes sis) = P(no bro) - P(sis and bro)

= 12/20 - 3/20

= 9/20

or 45%