A wheel turns at a rate of 12 turns every 5 seconds. If the wheel travels at a speed of 225 inches per second, what is the wheel's diameter?

12 turns/5s = 2.4 turns/s

each turn of a wheel of diameter d is πd inches, so

(225in/s)(1s/2.4rev) = 225/2.4 = 93.75 in/rev

so, πd = 93.75
d = 29.84 in