Question

On a map of North America, the scale is:

Answer 1

The scale factor as I understand it will just be 1 to 30, inches to miles.

however, in this case it seems to be suggesting a conversion to the same unit, say hmmm let's convert the miles to inches.

$\bf 30~\underline{mi}\cdot \cfrac{5280~\underline{ft}}{\underline{mi}}\cdot \cfrac{12~in}{\underline{ft}}\implies \cfrac{30\cdot 5280\cdot 12~in}{1}\implies 1900800~in\\\\ -------------------------------\\\\ \stackrel{in}{1}:\stackrel{mi}{30}\implies \stackrel{in}{1}:\stackrel{in}{1900800}$