Question

A box contains 6 red, 8 green,10 black 11 yellow and 12 white balls. What is the minimum number of

balls we have select from box to guarantee that 9 balls are of the same colours.

Answer 1

maximum of balls that we can draw such that there is no 9 balls are of the same colours:

6 red + 8 green +8 black + 8 yellow + 8 white = 38 balls

so, minimum number of balls we have select from box to guarantee that 9 balls are of the same colours:

$38+1=39$ balls