A semi-famous math professional poses this question in a book I'm reading.
I find the answer to be counter-intuitive, but, entertaining.
Here is the question:
You buy a sack of spuds that weighs 100lbs and are told it is 99% water.
You leave the sack outside in the sun for a couple of days before bringing it inside to store.
You find the spuds are now only 98% water.
How much does the sack of spuds weigh? Why?
(This is not a trick question. I'm not asking about the sack w/o the potato contents.)