Question

A box contains 10 white, 6 red and 10 black balls. A ball is drawn at

random from the box. What is the probability that the ball drawn is either

white or red?

Answer 1

There are total 10 + 6 + 10 = 26 balls So, the number of possible

outcomes is 26. Let W be the event of drawing white ball

$\therefore P\left(W\right)=\frac{10}{26}$

Let R be the event of drawing red ball

$\therefore P\left(R\right)=\frac{6}{25}$

By addition theorem,

$\therefore P(W\cup R)=P\left(W\right)+P\left(R\right)-P(W\cap R)$

[$\because$ W and R are mutually exclusive case]

$\therefore P(W\cap R)=0$

$\therefore \frac{10}{26}+\frac{6}{26}-0$

=$\frac{16}{26}=\frac{8}{13}$