1. Pre-Algebra HOMEWORK
Page 423
#31-38 &
Spiral Review (#39-45)
Answers

2. Page 427 #16-19 & Spiral Review (#20-24)
Pre-Algebra HOMEWORK
Page 427 #16-19 & Spiral Review (#20-24)

3. Our Learning Goal
Students will be able to determine and construct fractions, decimals, and percents by understanding their relationships, solving for the unknown, solving increase and decrease, solving sales tax/total cost contextual problems and compute simple interest.

4. Our Learning Goal Assignments
Learn to relate decimals, fractions, & percents (8-1)
Learn to find percents (8-2)
Learn to find a number when the percent is known (8-3)
Learn to find percent increase and decrease (8-4)
Learn to estimate with percents (8-5)
Learn to find commission, sales tax, and withholding tax (8-6)
Learn to compute simple interest (8-7)

5. Learning Goal Scale Students are able to determine & construct fractions, decimals, & percents:4 3 2 1
Clear understanding their relationships
Able to solve for the unknown
Understands how to solve for increase & decrease
Calculating solving sales tax/total cost contextual problems
Computing simple interest
Understands their relationships
Some solving for the unknown
Difficulty solving for increase & decrease
Difficulty solving for the unknown
Some understanding their relationships
Even with help, no understanding or skill demonstrated

6. Student Learning Goal Chart

7. Applications of Percents
8-6
Applications of Percents
Warm Up
Problem of the Day
Lesson Presentation
Pre-Algebra

8. Applications of Percents
Pre-Algebra
8-6
Applications of Percents
Warm Up
Estimate.
1. 20% of 602
out of 264
3. 151% of 78
out of 0.95
Possible answers:
120
50%
120
30%

9. Problem of the Day
What is the percent discount on a purchase of three shirts if you take advantage of the shirt sale?
All Shirts on Sale!
Buy 2—Get the Third
for Half Price! % 2 3

10. Today’s Learning Goal Assignment
Learn to find commission, sales tax, and withholding tax.

11. Vocabulary
commission
commission rate
sales tax
withholding tax

12. Real estate agents often work for commission
Real estate agents often work for commission. A commission is a fee paid to a person who makes a sale. It is usually a percent of the selling price. This percent is called the commission rate.
Often agents are paid a commission plus a regular salary. The total pay is a percent of the sales they make plus a salary.
commission rate  sales = commission

13. Additional Example 1: Multiplying by Percents to Find Commission Amounts
A real-estate agent is paid a monthly salary of $900 plus commission. Last month he sold one condominium for $65,000, earning a 4% commission on the sale. How much was his commission? What was his total pay last month?
First find his commission.
4%  $65,000 = c commission rate  sales = commission

14. Additional Example 1 Continued
0.04  65,000 = c Change the percent to a decimal.
2600 = c Solve for c.
He earned a commission of $2600 on the sale.
Now find his total pay for last month.
$ $900 = $ commission + salary = total pay
His total pay for last month was $3500.

15. Try This: Example 1
A car sales agent is paid a monthly salary of $700 plus commission. Last month she sold one sports car for $50,000, earning a 5% commission on the sale. How much was her commission? What was her total pay last month?
First find her commission.
5%  $50,000 = c commission rate  sales = commission

16. Try This: Example 1 Continued
0.05  50,000 = c Change the percent to a decimal.
2500 = c Solve for c.
The agent earned a commission of $2500 on the sale.
Now find her total pay for last month.
$ $700 = $ commission + salary = total pay
Her total pay for last month was $3200.

17. Sales tax is the tax on the sale of an item or service
Sales tax is the tax on the sale of an item or service. It is a percent of the purchase price and is collected by the seller.

18. Additional Example 2: Multiplying by Percents to Find Sales Tax Amounts
If the sales tax rate is 6.75%, how much tax would Adrian pay if he bought two CDs at $16.99 each and one DVD for $36.29?
CD: 2 at $ $33.98
DVD: 1 at $ $36.29
$70.27 Total Price
 = Convert tax rate to a decimal and multiply by the total price.
Adrian would pay $4.74 in sales tax.

19. Try This: Example 2
Amy rents a hotel for $45 per night. She rents for two nights and pays a sales tax of 13%. How much tax did she pay?
$45  2 = $90 Find the total price for the hotel stay.
$90  0.13 = $ Convert tax rate to a decimal and multiply by the total price.
Amy spent $11.70 on sales tax.

20. A tax deducted from a person’s earnings as an advance payment of income tax is called withholding tax.

21. Additional Example 3: Using Proportions to Find the Percent of Tax Withheld
Anna earns $1500 monthly. Of that, $ is withheld for Social Security and Medicare. What percent of Anna’s earnings are withheld for Social Security and Medicare?
Think: What percent of $1500 is $114.75?
Solve by proportion:
114.75
1500 n
100 =
n  1500 = 100  Find the cross products.

22. Additional Example 3 Continued
1500n = 11,475 Divide both sides by 1500.
11,475
1500 n =
n = 7.65
7.65% of Anna’s earnings is withheld for Social Security and Medicare.

23. Try This: Example 3
BJ earns $2500 monthly. Of that, $500 is withheld for income tax. What percent of BJ’s earnings are withheld for income tax?
Think: What percent of $2500 is $500?
Solve by proportion:
500
2500 n
100 =
n  2500 = 100  500 Find the cross products.

24. Try This: Example 3 Continued
2500n = 50,000 Divide both sides by 2500.
50000
2500 n =
n = 20
20% of BJ’s earnings are withheld for income tax.

25. Additional Example 4: Dividing by Percents to Find Total Sales
A furniture sales associate earned $960 in commission in May. If his commission is 12% of sales, how much were his sales in May?
Think: $960 is 12% of what number?
Solve by equation:
960 = 0.12  s Let s = total sales.
960
0.12
= s Divide each side by 0.12.
The associate’s sales in May were $8000.

26. Try This: Example 4
A sales associate earned $770 in commission in May. If his commission is 7% of sales, how much were his sales in May?
Think: $770 is 7% of what number?
Solve by equation:
770 = 0.07  s Let s represent total sales.
770
0.07
= s Divide each side by 0.07.
The associate’s sales in May were $11,000.

27. Lesson Quiz: Part 1
1. The lunch bill was $8, and you want to leave a 15% tip. How much should you tip?
2. The sales tax is 5.75%, and the shirt costs $20. What is the total cost of the shirt?
3. As of 2001, the minimum hourly wage was $5.15. Congress proposed to increase it to $6.15 per hour. To the nearest percent, what is the proposed percent increase in the minimum wage?
$1.20
$21.15
19%

28. Lesson Quiz: Part 2
4. It costs a business $13.30 to make its product. To satisfy investors, the company needs to make $4 profit per unit. To the nearest percent, what should be the company’s markup?
30%