Question

Mrs. Grundy has two children. Given that Mrs. Grundy has at least one child born on a Monday, what is the probability that both her children were born on Mondays? Assume that each child was equally likely to be born on any day of the week, and that the two birthdays are independent (Mrs. Grundy doesn't have twins!).

Answer 1

1/7

Explanation:

If one child was born on a Monday, then we don't have to consider that when solving the question, as it asks if both children were born on a Monday.

Thus, we only need to find the probability that the second child is born on a Monday. Since there are 7 days in a week and equally likely that the child is born on any day, then the probability of the child being born on a Monday would be 1/7.