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Question

Mathematics Question on Probability

From a group of 88 boys and 33 girls, a commitee of 55 members to be formed. Find the probability that 22 particular girls are included in the committe is

A

411\frac{4}{11}

B

211\frac{2}{11}

C

611\frac{6}{11}

D

811\frac{8}{11}

Answer

211\frac{2}{11}

Explanation

Solution

Total number of ways =8C23C3+8C33C2+8C43C1+8C53C0={ }^{8} C_{2}{ }^{3} C_{3}+{ }^{8} C_{3}{ }^{3} C_{2}+{ }^{8} C_{4}{ }^{3} C_{1}+{ }^{8} C_{5}{ }^{3} C_{0} =28×1+56×3+70×3+56×1=28 \times 1+56 \times 3+70 \times 3+56 \times 1 =462=462 Number of ways in which 22 particular girls are included PC3=84{ }^{P} C_{3}=84 \therefore\,\,\, Required probability =84462=211=\frac{84}{462}=\frac{2}{11}