Sunday Times Teaser 2747 – Marble Jar
by Michael Fletcher
Published: 17 May 2015 (link)
At our local fete one of the games consisted of guessing the number of marbles in a jar: some of the marbles were red and the rest were blue. People had to guess how many there were of each colour. The organiser gave me a couple of clues. Firstly, he told me that there were nearly four hundred marbles altogether. Secondly, he told me that if, when blindfolded, I removed four marbles from the jar, then the chance that they would all be red was exactly one in a four-figure number.
How many red marbles were there, and how many blue?