Diameter of wheel 

If a wheel travels 1 mile in 1 minute at a rate of 600 revolutions per minute. What is the diameter of the wheel in feet ? The answer to this question is 2.8 feet.


Could someone please explain how to solve this problem ?

The distance travelled by a wheel in one revolution is nothing but the circumference. If the circumference of the circle is $d$, then the distance travelled by the wheel on one revolution is $\pi d$.
It does $600$ revolutions per minute i.e. it travels a distance of $600 \times \pi d$ in one minute. We are also given that it travels $1$ mile in a minute.
Hence, we have that $$600 \times \pi d = 1 \text{ mile} = 5280 \text{ feet}\implies d = \dfrac{5280}{600 \pi} \text{ feet} \approx 2.801127 \text{ feet}$$
