Sunday Times Teaser 2490 – No Title
by Danny Roth
Published June 13 2010 (link)
George and Martha supply paint to the art class. They have 1l cans of red, yellow and blue, and can make 2l cans of orange (red and yellow equally), purple (red and blue) and green (yellow and blue), and 3l cans of brown (red, yellow and blue).
The class orders numbers of litres of all seven colours (totalling less than 500l), with the seven numbers forming an arithmetic progression. The lowest quantity is 1l; the highest can be shared equally among the class, each student getting a whole plural number of litres. George and Martha used equal quantities of blue and yellow making up the order.
How much green paint was ordered?