Q. A purse contains 4 copper and 3 silver coins. Another purse contains 6 copper and 2 silver coins. A coin is taken out from any purse, the probability that it is a silver coin, is
A) $\frac{37}{56}$
B) $\frac{19}{56}$
C) $\frac{4}{7}$
D) $\frac{2}{3}$
Explanation
(b)
Required probability$= \frac{1}{2}\left( \frac{\ ^{3}C_{1}}{\ ^{7}C_{1}} + \frac{\ ^{2}C_{1}}{\ ^{8}C_{1}} \right)$
$= \frac{1}{2}\left( \frac{3}{7} + \frac{2}{8} \right) = \frac{19}{56}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.