Fundamentals of Mathematics, 2008a

428 CHAPTER 7. RATIOS AND RATES
Exercise 7.3.6 (Solution on p. 467.)
7
x = 14
10
Exercise 7.3.7 (Solution on p. 467.)
9
11 = x 55
Exercise 7.3.8 (Solution on p. 467.)
1
6 = 8 x
7.3.4 Proportions Involving Rates
Recall that a rate is a comparison, by division, of unlike denominate numbers. We must be careful when
setting up proportions that involve rates. The form is important. For example, if a rate involves two types
of units, say unit type 1 and unit type 2, we can write
or
Both cross products produce a statement of the type
(unit type 1) · (unit type 2) = (unit type 1) · (unit type 2)
which we take to mean the comparison
Examples of correctly expressed proportions are the following:
However, if we write the same type of units on dierent sides, such as,
unit type 1 unit type 2
unit type 2
=
unit type 1
the cross product produces a statement of the form
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