Thursday, April 17, 2014

102: Watermelon

From Richard Wiseman:

I have a 100 pound watermelon laying out in the sun. 99% of the watermelon’s weight is water. After a few hours 98% of the watermelon’s weight is water. How much water evaporated?

The answer, slightly obscured for the sake of any who want to solve on their own, is 1100102 pounds – but can you explain why?


  1. See p. 135 of Andrei Toom's paper: "A Russian teacher in America", Journal of Mathematical Behavior 12 (1993), 117-139 (now freely available on the internet).

  2. I just downloaded that. Looks like I might get some more problems from there!