1. Warm up
Page TN 36 #2

2. Learn to solve percent problems that involve discounts, tips, and sales tax.

3. Vocabulary
discount
tip
sales tax

4. Common Uses of Percents
Sales tax is an amount added to the price of an item.
sales tax = price • sales tax rate
total cost = price + sales tax
Sales tax
A tip is an amount added to a bill for service.
tip = bill • tip rate
total cost = bill + tip
Tips
A discount is an amount that is subtracted from the regular price of an item.
discount = price • discount rate
total cost = price – discount
Discounts
Common Uses of Percents

5. Additional Example 1: Finding Discounts A clothing store is having a 10% off sale. If Angela wants to buy a sweater whose regular price is $19.95, about how much will she pay for the sweater after the discount?
Step 1: First round $19.95 to $20.
Step 2: Find 10% of $20 by multiplying 0.10 • 20. (Hint: Moving the decimal point one place left is a shortcut.)‏
10% of 20 = 0.10 • $20 = $2.00
The approximate discount is $2.00. Subtract this amount from $20.00 to estimate the cost of the sweater.
$20.00 – $2.00 = $18.00
Angela will pay about $18.00 for the sweater.

6. To multiply by 0.10, move the decimal point one place left.
Remember!

7. Check It Out: Example 1
A fishing store is having a 10% off sale. If Gerald wants to buy a fishing pole whose regular price is $39.95, about how much will he pay for the pole after the discount?
Step 1: First round $39.95 to $40.
Step 2: Find 10% of $40 by multiplying 0.10 • 40.
10% of 40 = 0.10 • $40 = $4.00
The approximate discount is $4.00. Subtract this amount from $40.00 to estimate the cost of the pole.
$ $4.00 = $36.00
Gerald will pay about $36.00 for the fishing pole.

8. When estimating percents, use percents that you can calculate mentally.
You can find 10% of a number by moving the decimal point one place to the left.
You can find 1% of a number by moving the decimal point two places to the left.
You can find 5% of a number by finding one- half of 10% of the number.

9. Additional Example 2: Finding Tips
Ben’s dinner bill is $7.85. He wants to leave a tip that is 15% of the bill. About how much should his tip be?
Step 1: First round $7.85 to $8.
Step 2: Think: 15% = 10% + 5%
10% of $8 = 0.10 • $8 = $0.80
Step 3: 5% = 10% ÷ 2
= $0.80 ÷ 2 = $0.40
Step 4: 15% = 10% + 5%.
= $ $0.40 = $1.20
Ben should leave about $1.20 as a tip.

10. Check It Out: Example 2
Lita’s dinner bill is $ She wants to leave a tip that is 15% of the bill. About how much should her tip be?
Step 1: First round $11.95 to $12.
Step 2: Think: 15% = 10% + 5%
10% of $12 = 0.10 • $12 = $1.20
Step 3: 5% = 10% ÷ 2
= $1.20 ÷ 2 = $0.60
Step 4: 15% = 10% + 5%.
= $ $0.60 = $1.80
Lita should leave about $1.80 as a tip.

11. Additional Example 3: Finding Sales Tax Ann is buying a dog bed for $ The sales tax rate is 7%. About how much will the total cost of the dog bed be?
Step 1: First round $29.75 to $30.
Step 2: Think: 7% = 7 • 1%
1% of $30 = 0.01 • $30 = $0.30
Step 3: 7% = 7 • 1%.
= 7 • $0.30 = $2.10.
The approximate sales tax is $2.10. Add this amount to $30 to estimate the total cost of the dog bed.
$30 + $2.10 = $32.10
Ann will pay about $32.10 for the dog bed.

12. Check It Out: Example 3. Erik is buying a blanket for $19. 83
Check It Out: Example Erik is buying a blanket for $ The sales tax rate is 8%. About how much will the total cost of the blanket be?
Step 1: First round $19.83 to $20.
Step 2: Think: 8% = 8 • 1%
1% of $20 = 0.01 • $20 = $0.20
Step 3: 8% = 8 • 1%
= 8 • $0.20 = $1.60.
The approximate sales tax is $1.60. Add this amount to $20 to estimate the total cost of the blanket.
$20 + $1.60 = $21.60
Erik will pay about $21.60 for the blanket.

13. Lesson Quizzes
Standard Lesson Quiz
Lesson Quiz for Student Response Systems

14. Lesson Quiz
1. Sean’s new jeans are priced at $29.97, but the sale sign reads, “Take 15% off.” About how much will the jeans cost after the discount?
2. The bill for a family dinner comes to $ About how much would a 20% tip be?
3. The price on a book is $ If sales tax is 4%, about how much will its total cost be?
4. Megan wants a new bike. She is happy to see a sign that reads, “All bikes 10% off.” If the original price of the bike was $ and sales tax is 6%, about how much will the total cost of the bike be?
about $25.50
about $11.50
about $13.50
about $150

15. Lesson Quiz for Student Response Systems
1. A pair of shoes is priced at $ During a sale, a discount of 20% is offered on it. About how much will the pair of shoes cost after the discount?
A. about $ B. about $36
C. about $ D. about $45

16. Lesson Quiz for Student Response Systems
2. Mary and her friends ordered lunch from a restaurant. The bill came to $ About how much would a home delivery charge of 15% be?
A. about $ B. about $4.20
C. about $ D. about $4.80

17. Lesson Quiz for Student Response Systems
3. The price of a pen is $6.60. If sales tax is 5%, about how much will its total cost be?
A. about $ B. about $7.26
C. about $ D. about $7.60

18. Lesson Quiz for Student Response Systems
4. Isaac wants to buy an MP3 player. The shop offers 10% discount on all MP3 players. If Isaac chooses an MP3 player whose original price is $49.85 and sales tax rate is 8%, about how much will he have to pay?
A. about $ B. about $46.40
C. about $ D. about $53.85