Practical Algebra, 3rd Edition

4RATIOS AND PROPORTIONS

As we said in Chapter 2, fractions have been a central part of number systems around the world for thousands of years. In this chapter, we focus on how we use fractions to compare quantities.

4.1 Expressing Ratios in Simplest Form

In Figure 4.1, the distance from point A to point B (AB) is 6 units, and the distance from point B to point C (BC) is 4 units.

Figure 4.1 Number line showing a 6:4 ratio.

To describe the relationship between AB and BC, we can use a ratio − a quantity that indicates how many times one number contains another. We express the number of times that AB contains BC in any of the following ways: ...