Question

A box contains 20 balls bearing numbers 1,2,3,....20 respectively . A ball is drawn at random from the box. Find the probability that the number on the ball is.
neither divisible by 3 or 5

Answer 1

Possible outcomes : $3,5,6,9,12,15,10,18$
$n=8$
Total no. of ball=$20$
$P\left(divisibleby3or5\right)=\frac{8}{20}=\frac{4}{5}$