Algebra 1 Companion Book, Vol 1 – Summer Edition

2.2.1 Rates, Ratios, and Proportions

Key Objectives • Write and solve proportions.

• Find unit rates. • Convert rates. • Convert units using proportions. Key Terms • A ratio is a comparison of two quantities using division. • A proportion is an equation that states that two ratios are equivalent. • A rate is a ratio that compares two quantities with different units of measure. • A unit rate is a rate where the comparison is to one unit. • A conversion factor is a fraction whose numerator and denominator represent the same quantity but use different units; the fraction is equal to 1 because the numerator and denominator are equal. • In a proportion, the cross product is the product of the numerator of one ratio with the denominator of the other ratio. Example 1 Using Ratios In Example 1, Prof. Burger demonstrates using a ratio to write a proportion, and solving a proportion.


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