Question

An experiment involves studying the composition of genders of a set of triplets What is the probability that there are 2 boys and a girl in the set?

a. 0.875
b. 0.125
c. 0.375
d. 0.625

Answer 1

Let's denote B for the birth of the boy and G for the birth of the girl.

There 8 possible outcomes:

BBB, BBG, BGB, GBB, BGG, GBG, GGB, GGG

There are 2 boys and a girl: BBG, BGB, GBB

Therefore the probability that there are 2 boys and a girl in the set is $\frac{3}{8}=0.375$

Answer: c 0.375.