Question:
What is the probability that a number selected from the numbers 1, 2, 3, ..., 15 is a multiple of 4?
Solution:
There are 15 numbers from $1,2, \cdots, 15$.
Hence, the total number of cases is 15 .
Again, the multiples of 4 are 4,8 and 12 .
Therefore, the total number of favourable cases is 3 .
$\therefore \mathrm{P}($ the number is a multiple of 4$)=\frac{\text { Number of favourable cases }}{\text { Total number of cases }}=\frac{3}{15}=\frac{1}{5}$