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Learn about proportions, cross products, and how to solve proportion problems with this helpful guide. Includes examples and a real-world application.
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PROPORTIONS 6-2
VOCABULARY • Proportion – equality of two ratios • Cross Products – the results when you cross multiply
KEY CONCEPTS • In a proportion, the ratios and the cross products are equal to each other. • Example: 6 = 8 ` 9 12 72 = 72
Examples… • Tell whether the two ratios form a proportion. 1. 6 = 4 2. 15 = 5 9 6 20 7 36 = 36 yes 105 = 100 no
To solve a proportion that contains a variable, cross multiply. • Example: x = 4 ` 9 6 6x = 36 Now you must get the x by itself, so take the number next to the variable and divide it on the other side. 6x = 36 6 x = 6
REAL WORLD PROBLEM • 100 nautical miles equals about 115 standard miles. To the nearest mile, how far in standard miles is 156 nautical miles? Nautical miles Standard miles 100 = 156 115 m 100m = 17,940 100m = 17,940 100 m = 179.4 156 nautical miles is about 179 standard miles