PERCENT PROPORTIONS

Using Proportions 4-1

Vocabulary Review

Ratio:The comparison of two numbers (written in

Algebra as a fraction)

Proportion:When two ratios are equal to each other

Cross Product(s):When we cross multiply/compare diagonally, the

special relationship between two ratios in a proportion

Percent Proportions

Proportions can be used to solve missing percentages of a number…

“is #” = given/missing % “of #” 100%

Percent Proportions

Ex.

Find 30% of 24.Is # =

Of # =

Given/missing % =

Write out proportion…

x = 30% 24 100%

*Round answer to nearest tenth of percent!

Ex.

What percent is 20 of 210?

Is # =

Of # =

Given/missing % =

Write out proportion…

= 100%

*Round answer to nearest tenth of percent!

We use the same steps to solve…

1) Cross multiply

2) Cross multiply

3) Divide to solve

Percent Proportions

Ex.What is 33 1/3% of 150?

x = 33.3%

150 100%

Ex.5 is 80% of what number?

5 = 80%

x 100%

Practice

A) 6% of what number is 2.46

B) What percent of 72 is 27?

C) Find 72% of 310.

Homework

p. 161 #9-20 all(Calculator okay!)

Show set up/process/work