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 110010

_{2}pounds – but can you explain why?

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).

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

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