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.)

The question doesn't say anything about the uniqueness of their ages...so, the neighbour could have had 4 sets of twins aged 5, 7, 11, 13 and another kid aged 19...

I think, in absence of any other information, this is a valid solution !

Posted by Syzygy on 2004-09-09 07:53:06