Question

On a tiny remote island where the death sentence still exists a man can be granted mercy after receiving the death sentence
He is given 18 red balls and 6 green balls
He must divide them between 3 boxes with at least one ball in each
He is blindfolded and must choose a box at random and then a single ball from within the box
He only receives mercy if a red ball is chosen
Find the probability that he recieves mercy when he distributes the balls in the most favourable mannor