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Using Proportions (Objective: using proportions to solve real world problems). MS. Battaglia / Mr. Baldino. Work together.
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Using Proportions(Objective: using proportions to solve real world problems) MS. Battaglia/ Mr. Baldino
Work together • A ratio is a comparison of two numbers by division. For example, ½ and 5:2 are ratios. The scale of a blueprint is the ratio of a length on the blueprint to the actual length it represents. Turn to page 158 in your textbooks and work on “Work Together” with a partner.
Using properties of equality • A proportion is a statement that two ratios are equal. Another way to write the sample at the right is 3:4 = 12:16. Read this “3 is to 4 as 12 is to 6.” • To solve a proportion with a variable, you can use the multiplication property of equality.
Example • Solve
Using cross products • The numerators and denominators of the ratios that form a proportion have a special relationship. The cross products of a proportion are equal. • When b ≠ 0 and d ≠ 0, • If then
Example • ΔABC is similar to ΔDFE. AB = 15, BC = 18, AC = 21, DF = 10. • Find DE. Similar figures have the same shape, but not necessarily the same size.
Aquaculture • In 1994, U.S. trout farms produced 52,000,000 lb of trout. Suppose a trout farmer raised 858,000 lb of trout. What percent of the 1994 U.S. trout production did the farmer raise? Round our answer to the nearest tenth of a percent.
Classwork/ Homework • 4-1 Worksheet