Can you solve this puzzle?

Zeb threw sixteen dimes as far as he could into a lake. Two of the dimes fell to the bottom of the lake and were buried in the muck. One of the dimes was swallowed by a carp. The other 13 dimes were hit by a lightning bolt and they flew up into the sky and were sprayed over a 10 mile circular radius. They each fell closer to the center of the circle than to the far end of the radius at the perimeter of the circle. The question is, what is the average distance of all the 13 dimes from the circle's center uming they fell in a statistical normal distribution?