Iwant to speed up a screw too 25 present the motor rpm is 1725 and grat box rato is 10.57 and the sprocket is a 15 tooth the driven sprocket is a 42 tooth so to speed up the screw to 25 present what sprocket do i change and how may tooth will need

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?