There are 800 families with four children in each family. Assuming equal chance for every child to be a boy…
There are 800 families with four children in each family. Assuming equal chance for every child to be a boy or a girl, the number of
families expected to have children of both sexes is
700
100
500
300
Solution
Given that 4 children in each family. Event of expected to have children of both sexes
\(=\frac{1}{2}\)
\(\therefore\) Probability of children of both sexes
\(\begin{aligned}
& =1-[P(\text { all boys })+P \text { (all girls)}] \\
& =1-\left\{\left(\frac{1}{2}\right)^4+\left(\frac{1}{2}\right)^4\right\} \\
& =1-\left(\frac{1}{16}+\frac{1}{16}\right)=1-\frac{1}{8}=\frac{7}{8}
\end{aligned}\)
Hence, the probability for 800 families
\(=\frac{7}{8} \times 800=700\)