Question

 750 families with 3 children were selected randomly and the following data recorded
If a family member is chosen at random, compute the probability that it has :

(i) no boy child
(ii) no girl child 

Answer 1

(i) P(no boy child) =100 / 750  = 2 / 15

(ii) P (no girl child) = 120 /750  =4 / 25

Answer 2

Given,

Total number of families = 750

Number of Families with 0 girl child = 120

Number of families with 1 girl child = 220

Number of families with 2 girl child = 310

Number of families with 3 girl child = 100

To find,

The probabilities that the family has (i) no boy child

(ii) no girl child.

Solution,

The required probabilities of having no boy child and no girl child are 2/15, 4/25 respectively.

Exhaustive cases = 750

Number of families having no boy child = Number of families having 3 girl child

Number of families having 3 girl child = 100

Probability = Favorable cases/Exhaustive cases

P( of getting no boy child) =100/750

                                           = 2/15

Number of families having no girl child = 120

P ( of getting no girl child ) = 120/750

                                            = 4/25

Hence, the required probabilities of having no boy child and no girl child are 2/25, 4/25 respectively.