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7.1 Ratios and Proportions Ratios Ratio: A comparison of two quantities by division. Ratios can be written in three ways… 1) The ratio of a to b 2) a : b 3) a , b0 b Ratios Find the ratio of the width of the photo to the poster. 5 in. 6 in. 1 2/3 ft. 2 ft. Proportions Proportion: A statement that two ratios are equal. a c b d or a : b c : d Determine if each of the following pairs of ratios are equal. 1) 1: 2 = 5 :10 5 3 2) ≠ 3 5 3) 10 18 = 15 27 Proportions a c Properties of Proportions: is equivalent to… b d b d a b ab c d 1) ad bc 2) 3) 4) a c c d b d Cross-Product Property: The product of the extremes is equal to of the means. the product Applying Properties x 5 If , complete each statement. y 6 1) 6x y 2) x 3) x 5 4) xy y Solving Proportions Solve the following proportions. y3 y 2) 8 4 x 12 1) 6 8 5 20 3) z 3 Ratios Scale: The ratio of any length in a scale drawing to the corresponding actual length. Ex. 1cm to 1ft or 1in = 10ft or 1mm : 100mi An inch ruler shows that l = 7/8 in. Find the actual length of the bedroom. Ratios Scale Drawing Activity!!! 20 point QUIZ grade #1-5 worth 2 points each #6 worth 10 POINTS! No more than 4 in a group •Must set up a proportion for each problem •Show all work on every problem •Answers must have the correct units of measure 7.1 Ratios and Proportions Homework #1 Pg 368 #2, 3-21 odd, 27, 30, 31, 35-43 odd