Question

If Swamy has two children and he truthfully answers yes to the question “Is at least one of your children a girl?”, what is the probability that both his children are girls?

• A. $\frac{1}{3}$
• B. $\frac{1}{2}$
• C. $\frac{2}{3}$
• D. 1

Answer 1

The correct option is B $\frac{1}{2}$

We know for sure that one of the children is a girl because Swamy is not lying.
That leaves us with two possibilities:- (Girl,Boy) and (Girl,Girl)
$\therefore$ Total cases = 2
Favourable cases = 1, i.e. (Girl,Girl)
$\therefore$ Required probability $=\frac{1}{2}$