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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:

Solution

✅ Correct Option: 1

The group contains:

Men = 3

Women = 2

Children = 4

Total people = 3 + 2 + 4 = 9


The total number of ways to choose 4 people from 9:

C(9,4)=9!4!×5!C(9,4) = \frac{9!}{4! \times 5!}

=9×8×7×64×3×2×1= \frac{9 \times 8 \times 7 \times 6}{4 \times 3 \times 2 \times 1}

=302424= \frac{3024}{24}

=126= 126


For exactly 2 children, the other 2 must be non-children (men or women).

Non-children = 3 + 2 = 5 people

Choosing 2 children from 4:

C(4,2)=4×32×1=6C(4,2) = \frac{4 \times 3}{2 \times 1} = 6

Choosing 2 non-children from 5:

C(5,2)=5×42×1=10C(5,2) = \frac{5 \times 4}{2 \times 1} = 10

Total favorable outcomes = 6×10=606 \times 10 = 60


The probability is:

P=60126P = \frac{60}{126}

=1021= \frac{10}{21}

Therefore, the probability that exactly 2 of them are children is 1021\frac{10}{21}.

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