A factory produces 139968 tennis balls a day. There are 204 people working on the production line in the factory. Estimate the number of balls made per person each day.
To estimate the number of balls made per person each day, we divide the total number of tennis balls produced (139,968) by the number of workers (204):
139,968 / 204 ≈ 686.4
Therefore, each person on the production line is estimated to make approximately 686.4 tennis balls per day.