Q. The probability that in a family of 5 members, exactly 2 members have birthday on sunday, is
A) $\frac{12 \times 5^{3}}{7^{5}}$
B) $\frac{10 \times 6^{2}}{7^{5}}$
C) $\frac{2}{5}$
D) $\frac{10 \times 6^{3}}{7^{5}}$
Explanation
(d)
Probability of getting a Sunday in a week,
$p = \frac{1}{7},\ q = \frac{6}{7}$
Required probability$= \ ^{5}C_{2}\left( \frac{1}{7} \right)^{2}\left( \frac{6}{7} \right)^{3} = \frac{10 \times 6^{3}}{7^{5}}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.