Number - Revolutions

[Guest]

A wheel travels a miles and the radius of the wheel is b inches. Calculate number of revolutions.

Partial answer provided with problem:

31,680 x a / pi x b

How was the 31,680 calculated ? Thank you.

[Guest]

Please respond. Thanks again.

[Guest]

One mile is 1760 yards
OR 3 x 1760 = 5280 feet
OR 63360 inches.

The circumference of a circle is Pi x diameter OR Pi x 2 x radius

The radius is "b" inches OR diameter is "2xb" inches

So number of revolutions is (63360 x a) / (Pi x 2 x b)

The 2 divides in to 63360 to give 31680

and so leaves (31680 x a) / (Pi x b)

[Guest]

I understand now - Thanks.