Question

There are $500$ wrist watches in a box. Out of these $50$ wrist watches are found defective. One watch is drawn randomly from the box. Find the probability that wrist watch chosen is a defective watch.

Answer 1

Total number of watches $n\left(S\right)=500$
Number of defective watches $n\left(A\right)=50$
$P\left(A\right)=\frac{n\left(A\right)}{n\left(S\right)}$
$\Rightarrow P\left(A\right)=\frac{50}{500}$
Probability of watch to be defective $=\frac{1}{10}$