We use a map to find out how to get from one place to another. We also use it to estimate what the driving distance is between point A and point B and plan out the alternative or shortest route to get there.  Maps are often drawn to a reduced scale such as 1 inch to 20 miles. If they were drawn to the full scale, you’d have to have a pretty big piece of paper. For a world map, you would virtually need a sheet of paper larger than the world itself!

Ratio is the mathematical concept that is used to develop scaled maps. If mapmakers do not use the concept of ratio, their maps will not be to scale. As a result, you may misjudge the actual distance where you want to go.

The equation for finding the distance between two cities on a map is:

D = d ´ S

where

d = distance on map in inches

S = scale (miles/inch)

D = actual distance in miles

From City A to City B, it is 5 inches on the map. Each inch equals 13 miles. How many miles is the actual distance?

D = d ´ S

D = 5 ´ 13

D = 65

The actual distance is 65 miles.

You are drawing a map of your city for a school project. The area is 33 miles by 20 miles and you want to show it on a standard piece of 11"x 8.5" paper. What scale should you draw the map to?

Estimate the answer:

1" to 2 miles

1" to 3 miles

1" to 5 miles

1" to 10 miles