Tennis serve?

Question

what is the fastest tennis serve for a 12 year old?

Answer 1

I heard Sampras serve was close to 80 mph when he was like 13 or 14 years old.  Not sure if it was true, but for a 12 year old, nobody really knows :)

Answer 2

Andy Roddick owns the record for the fastest serve in ATP history. It was 155 MPH. It was during the Davis Cup semifinals match. It was against Vladimir Voltchkov. Their match was played on hard court.

and as for twelve year olds i do not know