Answer
$0.75$
Work Step by Step
We know that $probability=\frac{number \ of \ good \ outcomes}{number\ of\ all\ outcomes}$ and by the inclusion-exclusion principle:$P(A \cup B)=P(A)+P(B)-P(A\cap B)$. A:getting a baby girl
B:if tossing a coin, getting a head. By checking the data:
$P(A)=\frac{1}{2}$
$P(B)=\frac{1}{2}$
$P(A\cap B)=\frac{1}{2}\cdot\frac{1}{2}=\frac{1}{4}$
Therefore getting a baby girl or if tossing a coin, getting a head: $P(A \cup B)=\frac{1}{2}+\frac{1}{2}-\frac{1}{4}=\frac{3}{4}=0.75$
