Four Coloured Bottles

Posted May 6 - 12, 1996

a) Which bottle is just about to fall?

The yellow bottle is about to fall.b) How many possible orderings are there for the bottles, and what are they?

Left: Green Blue Red Yellow :RightNo other orderings are possible in order to meet the conditions.

Ian MacLennan (petermac@wchat.on.ca) sent Minus this thorough, but correct solution:

Since the red bottle is beside the yellow and blue bottles, and the blue is beside the green and red, the order of the bottles must be either yellow red blue green or green blue red yellow. Since the green bottle is not about to fall, the order must be green, blue, red, yellow, and therefore the yellow bottle must be about to fall.