Crossroads in Mathematics

Example 4

Proportional Relationships

Students should know how to use the idea of proportions as a basic problem solving strategy.

Problem. Decide if a proportional relationship is present in each of the following situations. If so, describe the relationship and use it to solve the problem.

a. In one small office within a corporation, 6 out of 9 management positions are held by women. If that rate holds throughout the corporation, how many of the 180 management positions are held by women?

b. One inch is the same length as 2.54 cm. About how many inches is 75 cm?

c. If the length of a side of a triangle is 3 in. and its area is 9 sq. in., what is the length of the corresponding side of a similar triangle whose area is 36 sq. in.?

d. The scale on a road map is 1 inch = 20 miles. How many miles are there between two cities 11.5 inches apart on a map?