Question

A box contains $20$ balls bearing numbers, $1,2,3,4,.....,20$. A ball is drawn at random from the box. What is the probability that the number on the ball is divisible by $2$ or $3$.

• A. $\frac{6}{10}$
• B. $\frac{11}{20}$
• C. $\frac{13}{20}$
• D. None of these

Answer 1

Answer: (C)

$\frac{13}{20}$

Here, total numbers are $20$.
$\therefore$ Total number of elementary events $=20$
Number divisible by $2$ or $3$ are $\{2,3,4.6,8.9,10.12.14,15,16,18,20\}$.
Favourable number of elementary events $=13$
$P($Number divisible by $2$ or $3)=$ $\frac{13}{20}$.