Sunday Times Teaser 2768 – In the Bag
by Richard England
Published: 11 October 2015 (link)
A set of snooker balls consists of fifteen reds and seven others. From my set I put some into a bag. I calculated that if I picked three balls out of the bag simultaneously at random, then there was a one in a whole-number chance that they would all be red. It was more likely that none of the three would be red — in fact there was also a one in a whole-number chance of this happening.
How many balls did I put in the bag, and how many of those were red?