Puzzler of the week

[Scott MacLean]

This week's puzzler:

In 1982, John is 12 years old. 1987 John is seven years old. How can that be? Hint: his name probably wasn't John.

Last week's puzzler:

A farmer had a 40-pound stone, which he could use to weigh 40 pounds of feed; he would sell feed in 40 pounds, or bales of hay, or whatever. He had a balance scale; he put the stone on one side and pile the other side with feed or hay, and when it balanced, that's it.

A neighbor borrows the stone, but he had to apologize when he returned it, broken into four pieces. The farmer who owned the stone later told the neighbor that he actually had done him a favor. The pieces of the broken stone could now be used to weigh any item, assuming those items were in one-pound increments, from one pound to 40.

What were the weights of the four individual stones?

Last week's puzzler answer:

Clearly, one of the pieces has to be one pound. The next one will be three.

That's what it was, it was in the Math group. That somehow I figured out it had to be powers of three, because if it broke into four pieces, there are four powers of three between one and 40 -- three to the zero which is one, three to the one which is three, three squared which is nine and three cubed which is 27.

So the answer is: One, three, nine and 27.