Problem of the Week
for Friday, Oct 31

Ants have gotten into Mr. Swacker's candy supply! Their trail runs from the door of 9-1 straight to the candy cupboard. To combat the problem, Mr. Swacker has placed his pet anteater, Boris, outside the door. Any ants that come our are immediately devoured.

There are only three ants left. One is at the door headed for the cupboard, one is just leaving the cupboard (its mandibles stuffed with delicious candy) and the third is halfway along and headed for the door. If the entire trail is twelve feet long and the ants crawl at a rate of one inch per second, how long before the last ant is eaten?

(Note about ant behaviour: these ants crawl along in single file and always stay on the trail. When they reach the cupboard, they immediately grab a mouthful of candy and turn around. When two ants bump into each other they both change direction.)