Question: How many different types of tennis ball exist . . .?
Answer: In theory, there could be
24 different kinds of balls. Tennis balls come in four speeds, three types of felt, and two basic means for producing bounce, but some of these combinations are illogical or simply not produced, leaving 16 that you might find if you looked hard enough and only four that you'd find in most pro shops:
- pressureless, medium speed, extra duty felt
- pressurized, medium speed, regular felt
- pressurized, medium speed, extra duty felt
- pressurized, slow speed, extra duty felt

