CPM Homework Help : INT2 Problem 9-123

Multiple Choice: Jill’s car tires are spinning at a rate of $120$ revolutions per minute. If her car tires’ radii are each $14$ inches, how far does she travel in $5$ minutes?

$140\pi \; \text{in}$

$8400\pi \; \text{in}$

$3360\pi \; \text{in}$

$16800\pi \; \text{in}$

Hint:

Circumference $= 2$ * $π$ * diameter 'revolution'.
In this case, our diameter is $14$ inches.
We also know we have $120$ revolutions per minute, with $5$ minutes given.

Answer:

By using dimensional analysis, we see that the circumference multiplied by the
total revolutions gives us $16800π$ inches. The answer is D.