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7.1_Ratios_and_proportions.notebook 7.1 ­ Ratios and Proportions February 23, 2010 What is a ratio? Objective: To write ratios and solve proportions Real ­ World Ratios Example • An F­15 aircraft produces 50,000 lb of thrust and weighs 44,500 lbs. What is its thrust­to­weight ratio? Write the ratio two different ways. • Aspect ratio (width to height) of your TV/Computer screen Widescreen TV's have an aspect ratio of 16:9 • Strength­to­weight ratio for materials • Thrust­to­weight ratio for an airplane • Body Mass Index is a ratio of your height to your weight squared Proportions Properties of Proportions A proportion is a statement that two ratios are equal. a c It can be written as = b d Widescreen TV dimensions Write the proportionality statement for the TV dimensions (Width­to­height): Screen width Screen height 46 " TV 40" 22.5" 55" TV 48" 27" 1 7.1_Ratios_and_proportions.notebook Solving Proportions 1. 3. 2. February 23, 2010 Applying Proportions A recipe calls for 4 cups of flour and 6 eggs, but you only have 4 eggs. How much flour should you use? 4. Scale Factor A scale factor allows you to find the actual measurement from a scaled object or drawing. Applying Scale Factors The architecture drawing at the right shows a scale factor of 1 in. = 16 ft. The length of the bedroom in the drawing is 1.25 inches. What is the length of the actual bedroom? Homework Pg. 369 #13 ­ 21 odd, 26, 27, 28 & 35 ­ 43 odd 2 Attachments f­22.mp4