Four people are chosen at random from a group of 3 men, 2 women and 4 children. The probability that exactly 2 of them are children is: |
$\frac{10}{21}$ $\frac{1}{9}$ $\frac{1}{12}$ $\frac{1}{5}$ |
$\frac{10}{21}$ |
The correct answer is Option (1) → $\frac{10}{21}$ Step 1: Total group
$\begin{pmatrix}9\\4\end{pmatrix} = \frac{9 \cdot 8 \cdot 7 \cdot 6}{4 \cdot 3 \cdot 2 \cdot 1} = 126$ Step 2: Ways to choose exactly 2 children
$\begin{pmatrix}4\\2\end{pmatrix} = 6$
$\begin{pmatrix}5\\2\end{pmatrix} = 10$
$6 \times 10 = 60$ Step 3: Probability $P = \frac{\text{favorable ways}}{\text{total ways}} = \frac{60}{126} = \frac{10}{21}$ |