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:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → $\frac{10}{21}$
Step 1: Total group
- 3 men + 2 women + 4 children = 9 people
- Total ways to choose 4 people out of 9:
$\begin{pmatrix}9\\4\end{pmatrix} = \frac{9 \cdot 8 \cdot 7 \cdot 6}{4 \cdot 3 \cdot 2 \cdot 1} = 126$
Step 2: Ways to choose exactly 2 children
- Number of ways to choose 2 children out of 4:
$\begin{pmatrix}4\\2\end{pmatrix} = 6$
- Remaining 2 people must be chosen from 3 men + 2 women = 5 people:
$\begin{pmatrix}5\\2\end{pmatrix} = 10$
- Total favorable ways:
$6 \times 10 = 60$
Step 3: Probability
$P = \frac{\text{favorable ways}}{\text{total ways}} = \frac{60}{126} = \frac{10}{21}$