7-1 Ratios and Proportions

Class Notes and Examples

Notes A ratio is a comparison of two quantities

using division. i.e. For every 2 apples in my fridge, there are 4

oranges.

An extended ratio compares three or more quantities. i.e. For every 2 apples in my fridge there are 4

oranges and 6 kiwi

After writing a ratio, reduce it as far as possible.

Example 1.) A pigmy rattlesnake has an average length

of 18 in., while a Western diamondback rattlesnake averages a length of 5 ft 6 in. What is the ratio of the length of a pigmy rattlesnake to the length of a Western diamondback rattlesnake?

Notes You can also use a given ratio to write and

solve equations.

Examples 2.) The measures of two complementary

angles are in the ratio of 1 : 3. What are the measures of the angles?

Examples 3.) The lengths of the sides of a triangle are in

the extended ratio 2 : 4 : 5. The perimeter of the triangle is 77 in. What is the length of the longest side?

Notes A proportion is an equation that shows that

two ratios are equivalent, or equal. If the proportion contains a variable, you can

solve for it by cross multiplying (multiply the values on diagonal and set them equal to each other).

Notes

Examples

Examples