Question

A ball is drawn from a box containing 6 red balls, 4 white balls and 5 black balls . What is the probability that it is not red ball?

Answer 1

The total number of outcomes:

$N=6+4+5=15.$

The number of favorable outcomes (the drawn ball is white or black):

$n=4+5=9.$

The probability that the drawn ball is not red ball:

$P=\cfrac{n}{N}=\cfrac{9}{15}=\cfrac{3}{5}=0.6.$