Find the total number of selections of at least one red ball from a bag containing 4 red balls and 5 black balls, balls of the same colour being identical.

Explanation

Number of sections of atleast one red ball from 4 identical red balls=4
Number of selections of any number of black balls from 5 identical black balls
=5+1=6
`therefore`Required number of selection of balls
`=4xx6=24`.