The probability of selecting a rotten apple randomly from a heap of 900 apples is 0.18.
Question:

The probability of selecting a rotten apple randomly from a heap of 900 apples is 0.18. What is the number of rotten apples in the heap?

Solution:

Total number of apples = 900.
P(a rotten apple) = 0.18

$\Rightarrow \frac{\text { number of rotten apples }}{\text { total number of apples }}=0.18$

$\Rightarrow \frac{\text { number of rotten apples }}{900}=0.18$

$\Rightarrow$ The number of rotten apples $=0.18 \times 900=162$ apples.