Question

A bag contains $6$ white and $4$ black balls. Another bag contains $4$ white and $6$ black balls. A die is rolled and if it shows a prime number a ball is taken from the 1st bag, otherwise a ball is taken from the second bag. The probability that the ball drawn is white is

• A. $\frac{1}{2}$
• B. $\frac{3}{5}$
• C. $\frac{2}{5}$
• D. $\frac{1}{4}$

Answer 1

The correct option is A $\frac{1}{2}$

P (getting prime) $=3/6=1/2$
P (getting white ball) $=\frac{1}{2}\ast \frac{6}{10}+\frac{1}{2}\ast \frac{4}{10}=\frac{1}{2}$