PROPORTIONS

6-2

VOCABULARY

Proportion – equality of two ratiosCross 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 66x = 36

Now you must get the x by itself, so reverse the operation.6x = 36

6 6

x = 6

REAL WORLD PROBLEM100 nautical miles equals about 115 standard miles. To the nearest mile, how far in standard miles is 156 nautical miles?

Nautical milesStandard miles

100 = 156 115 m100m = 17,940

100m = 17,940 100 100

m = 179.4 156 nautical miles is about 179 standard miles