Percents and Proportions

Setup of a Percent Proportion

• Is = part

• Of = whole

is

ofpercent

100

Example

• In Arkansas, the state sales tax is 4.5%. You want to buy a $195 bicycle in Arkansas. How much is the tax?

Example

• In Arkansas, the state sales tax is 4.5%. You want to buy a $195 bicycle in Arkansas. How much is the tax?

• $8.78

Example

• Suppose 11,550 elementary students make up 14% of a city’s population. What is the population of the city?

Example

• Suppose 11,550 elementary students make up 14% of a city’s population. What is the population of the city?

• 82,500

Example

• Write a proportion to solve each problem.

• C) Find 12.5% of 90

• D) Find 5.75% of 1000

Example

• Write a proportion to solve each problem.

• A) Find 25% of 120

• B) Find 85% of 150

Your Turn

• A) 10 is 25% of what number?

• B) 36 is 75% of what number?

Practice Problem

• What percent of 60 is 15?

What are we looking for?

What is the base?

What is the part? How do we set up the proportion?percent

60, remember “of”

15, remember “is” 15

60p

100

Solve15

60p

100

Step 1: Cross multiply 15 x 100 = 60 x p

Step 2. Simplify

1500 = 60p

Step 3. Solve for p

1500/60 = p

15 is 25% of 60 P= 25%

Your turn

• What percent of 25 is 30?

• Remember:

• Identify base, part

• What is the unknown

• How do we set it up?

Your turn answer

• 120%

Practice problems

• 1) What number is 40% of 80?

• 2) 75 is 20% of what number?

• 3) What percent is 45 of 60?

• Remember: identify what you know, what you are solving for, set up proportion and solve.

Practice problems answers

• 32

• 375

• 75%