3 Tennis balls are stacked in a canister as pictured below. If the radius of the tennis ball is 2 cm, the height of the canister is 14 cm and the radius of the canister is 2.5 cm, what volume of air is left over in the canister around the tennis balls?

Margie is practicing for an upcoming tennis tournament. her first serve is good 20 out of 30 times on average. margie wants to know the estimated probability that her first serve will be good at least four of the next six times she serves. how could she design a simulation for this scenario?