My neighbor has nine kids (all under 21), and their ages are such that you can never pick three kids so that the middle one is the average of the ages of the extreme ones. What are their ages?

(Note that you could also say that you can never find three kids whose ages are in arithmetic progression.)

(In reply to Valid Solution ? - I think so ! by Syzygy)

your solution cannot be correct, if you select one of the 7yo twins and the 19yo, the average age is 13, which is not allowed as you have twins that old.

Posted by Juggler on 2004-09-09 08:10:17