There are two balls in an urn. Each ball can be either white or black. If a white ball is put into the urn…
There are two balls in an urn. Each ball can be either white or black. If a white ball is put into the urn and there after a ball is drawn at random from the urn, then the probability that it is white is
$\frac{1}{4}$
$\frac{2}{3}$
$\frac{1}{5}$
$\frac{1}{3}$
Solution
Total possible event when one ball is taken out $={ }^3 \mathrm{C}_1$ Let $E$ : The event of 1 white ball coming out
No. of ways to 1 white ball coming out $={ }^2 \mathrm{C}_1$
$
\therefore P(E)=\frac{{ }^2 C_1}{{ }^3 C_1}=\frac{2}{3}
$