Question

An urn A contains 8 black and 5 white balls. A second urn B contains 6 black and 7 white balls.A blind folded persons is asked to draw a ball selecting one of the urns, the probability that the ball drawn is white is

• A. $\frac{5}{13}$
• B. $\frac{6}{13}$
• C. $\frac{7}{13}$
• D. $\frac{9}{13}$

Answer 1

The correct option is B $\frac{6}{13}$

Urn 1: $8B+5W=13$ balls
Urn 2: $6B+7W=13$ balls
Selection of an urn is$=\frac{1}{2}$
Probability that the one drawn ball is white$=\frac{1}{2}[\frac{5}{13}+\frac{7}{13}]=\frac{6}{13}$