Q. If birth to male child and birth to female child are equal-probable, then what is the probability that at least one of the three children born to a couple is male?
A) $\frac{4}{5}$
B) $\frac{7}{8}$
C) $\frac{8}{7}$
D) $\frac{1}{2}$
Explanation
(b)
Let $S = \{ BBB,\ BBG,\ BGB,\ GBB,\ GGB,\ GBG,\ BGG,\ GGG\}$
and $E = \left\{ BBB,\ BBG,\ BGB,\ GBB,\ GGB,\ GBG,\ BGG \right\}$
$\therefore P(E) = \frac{n(E)}{n(S)} = \frac{7}{8}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.