1. Day 2: Proportions Notes
Module 3: Proportional Reasoning

2. Review Key Vocabulary
Proportional – when two quantities simplify to the same ratio.
Constant – a quantity having a value that does not change or vary.
Constant of Proportionality - a constant value of the ratio of two proportional quantities.

3. Review
As stated yesterday, a proportion is two ratios/fractions equal to each other. You created equivalent fractions yesterday.
A proportion allows you to create equivalent ratios using algebra.
You need to be able to solve one-step equations in order to solve proportions.
Solve the following equations:
1. 3x = x = x = x = 14

4. Exercise: Babysitting
You have been hired by your neighbors to babysit their children on Friday night. You are paid $8 per hour. Complete the table relating your pay to the number of hours you worked.
Hours Worked
Pay ($) 1 2 3 4
4.5 5 6
6.5

5. Example 2 x Number of Days y Cost 6 2 9 3 24 8 1
Determine if y is proportional to x. Justify your answer. The table below shows the relationship between cost of renting a movie to the number of days on rent. x
Number of Days y
Cost 6 2 9 3 24 8 1

6. Example 3
Determine if y is proportional to x. Justify your answer. The table below shows the relationship between the amount of candy (pounds) bought and the total cost. x
Pounds y
Cost 5 10 4 8 6 12 16 20

7. Creating Proportions
When creating proportions, you can set up your proportion in several ways. The key to creating them is always match up corresponding parts or wholes.
Example: In a Valentine's Day bouquet, 2 out of every 5 roses are pink. If there are 6 pink roses, how many total roses are in the bouquet?

8. Practice
1. Rita made 12 pairs of earrings in 2 hours. How many pairs of earrings could she make in 3 hours?

9. Practice
2. Perry earned $96 shoveling snow from 8 driveways. How much would Perry have earned if he had shoveled 10 driveways?

10. Practice
3. Marlene is planning a trip. She knows that her car gets 38 miles to the gallon on the highway. If her trip is going to be 274 miles and one gallon of gas is $2.30, how much should she expect to pay for gas?

11. Multi-Step with proportions
1. For every 3 boys at soccer camp, there are 2 girls. If there are 20 children at soccer camp, how many are girls?

12. Multi-Step with proportions
2. It takes Ryan about 8 minutes to type a 500 word document. How long will it take him to type a 12 page essay with 275 words per page?