A survey was conducted on 300 families having 2 children each. The results obtained are given below.

Number of girl child	Number of families
2	95
1	165
0	40
Total	300

If one family is selected at random, find the probability that it will have:

(a) one girl child

(b) one or more girl child

(c) no boy child

(a) Total number of families = 300

Let E be the event of selecting family with one girl child,

∴ Number of favorable outcomes = 165

P(E) = $\dfrac{\text{Number of favorable outcomes}}{\text{Total number of outcomes}} = \dfrac{165}{300} = \dfrac{11}{20}.$

Hence, probability of selecting family with one girl child = $\dfrac{11}{20}.$

(b) Let A be the event of selecting family with one or more girl child,

∴ Number of favorable outcomes = 165 + 95 = 260

P(A) = $\dfrac{\text{Number of favorable outcomes}}{\text{Total number of outcomes}} = \dfrac{260}{300} = \dfrac{13}{15}.$

Hence, probability of selecting family with one or more girl child = $\dfrac{13}{15}.$

(c) Let B be the event of selecting family with no boy child.

A family will have no boy child, if there are 2 girl child in the family.

∴ Number of favorable outcomes = 95

P(B) = $\dfrac{\text{Number of favorable outcomes}}{\text{Total number of outcomes}} = \dfrac{95}{300} = \dfrac{19}{60}.$

Hence, probability of selecting family with no boy child = $\dfrac{19}{60}.$