
is the equation used for determining area from radius. We're given diameter, so to get the radius simply divide by 2. 19/2 = 9.5.

, when solved, equals

. After rounding to the nearest tenth, we get
Prime numbers 2,3,5,7,11,13,17,19,23
so 2+3+5=10 no
3+5+7=15 no
3+5+11=19 Yes this is your answer