Question

A tennis player lands 25 out of 40 first serves in bounds for a success rate of 62.5%. How many more consecutive first serves must she land in bounds to increase her success rate to 70%.

Answer 1

She will need to make 10 more consecutive first serves until the number of serves in out of the total number of serves is equal to 70%.

Start with 25/40, then 26/41, 27/42, 28/43, 29/44, 30/45, 31/46, 32/47, 33/48, 34/49, 35/50 (70%).