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?

I've just read most of the posts and I have this to offer:

1 (language) "fewest number" does not make sense; it should read  "what is the smallest number.."

2. The question should also specify that one cannot physically compare the weights by hand (when putting them on the scale). For example, you number them and then says which numbers weights to use at each step.

3. Most important: the problem asks for the least number of wighings. So a correct solution would not only contain a procedure (algorithm) that ALWAYS leads to the ranking of the weights, but also an argument (proof) that it cannot be done in fewer weighings.

Enjoy!

Posted by foto on 2004-09-09 20:14:25