You have 4 weights weighing 2,3,5 and 7 pounds. The problem is none of them are marked. What is the fewest number of weighings you need using a balance scale figure out which weights are which?
(In reply to
re: My son's solution by ron)
He is 15
Yes He did understand it.
Yes I did pose this puzzle to him although it is Provably Unprovable.