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2-6 Ratios and Proportions. Ratio: A comparison of 2 numbers by division. Either using a colon or, more commonly in this chapter, as a fraction. Proportion: An equation stating that two ratios are equal. Determine whether the ratios form proportions. Therefore, the ratios form a proportion.
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2-6 Ratios and Proportions • Ratio: A comparison of 2 numbers by division. Either using a colon or, more commonly in this chapter, as a fraction. • Proportion: An equation stating that two ratios are equal.
Determine whether the ratios form proportions Therefore, the ratios form a proportion.
Means & Extremes • In a proportion, the product of the extremes is equal to the product of the means. • If then ad = bc. Cross Multiply.
Use cross products (cross multiplication) to determine whether each pair of ratios forms a proportion. No, so it is not a proportion. Yes, so it is a proportion.
8n = 12(3) 8n = 36 8n/8 = 36/8 n = 4.5 n(30) = 18(15) 30n = 270 30n/30 = 270/30 n = 9 Solve Using Cross Multiplication
The gear on a bicycle is 8:5. This means that for every 8 turns of the pedals, the wheel turns 5 times. Suppose the bicycle wheel turns about 2435 times during a trip. How many times would you have to crank the pedals during the trip? 8(2435) = 5n 19480 = 5n 19480/5 = 5n/5 3896 = n 3896 turns Use rates
In a road atlas, the scale for the map of Connecticut is 5 inches = 41 miles. The scale for the map of Texas is 5 inches = 144 miles. What are the distances in miles represented by 2 ½ inches on each map? Connecticut: Texas: Using a Scale Drawing
Homework #15 • Practice Worksheet 2.6