Question:
A bag contains 5 white and 7 red balls. One ball is drawn at random. What is the probability that ball drawn is white?
Solution:
Number of white balls $=5$
Number of red balls $=7$
Total number of balls $=5+7=12$
$\therefore$ The total number of cases $=12$
Again, there are 5 white balls. Therefore, the number of favourable outcomes is 5 .
$\therefore \mathrm{P}($ the drawn ball is white $)=\frac{\text { Number of favourable cases }}{\text { Total number of cases }}=\frac{5}{12}$