Question

A bag contains 4-balls, two balls are drawn from the bag and are found to be white then probability that all balls in the bag are white is

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

Answer 1

The correct option is C $\frac{3}{5}$

$P\left(E\right)=\frac{\frac{1}{3}.\frac{4_{C_2}}{4_{C_2}}}{\frac{1}{3}\{\frac{2_{C_2}}{4_{C_2}}+\frac{3_{C_2}}{4_{C_2}}+\frac{4_{C_2}}{4_{C_2}}\}}=\frac{1}{\frac{1+3+6}{6}}=\frac{6}{10}=\frac{3}{5}$