Question:
An urn contains 10 red and 8 white balls. One ball is drawn at random. Find the probability that the ball drawn is white.
Solution:
Number of red balls $=10$
Number of white balls $=8$
Total number of balls in the urn $=10+8=18$
Therefore, the total number of cases is 18 and the number of favourable cases is 8 .
$\therefore \mathrm{P}$ (The ball drawn is white) $=\frac{\text { Number of favourable cases }}{\text { Total number of cases }}=\frac{8}{18}=\frac{4}{9}$