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7-10 Applying PercentsWarm up
• Page TN 36 #2
7-10 Applying Percents
Learn to solve percent problems that involve discounts, tips, and sales tax.
7-10 Applying Percents
Vocabulary
discounttipsales tax
7-10 Applying 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
7-10 Applying Percents
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.
7-10 Applying Percents
To multiply by 0.10, move the decimal point one place left.
Remember!
7-10 Applying Percents
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. $40.00 - $4.00 = $36.00
Gerald will pay about $36.00 for the fishing pole.
7-10 Applying Percents
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.
7-10 Applying Percents
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%
Step 3: 5% = 10% ÷ 2
= $0.80 ÷ 2 = $0.40Step 4: 15% = 10% + 5%.
Ben should leave about $1.20 as a tip.
= $0.80 + $0.40 = $1.20
10% of $8 = 0.10 • $8 = $0.80
7-10 Applying Percents
Check It Out: Example 2
Lita’s dinner bill is $11.95. 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%
Step 3: 5% = 10% ÷ 2
= $1.20 ÷ 2 = $0.60Step 4: 15% = 10% + 5%.
Lita should leave about $1.80 as a tip.
= $1.20 + $0.60 = $1.80
10% of $12 = 0.10 • $12 = $1.20
7-10 Applying Percents
Additional Example 3: Finding Sales Tax Ann is buying a dog bed for $29.75. 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.
7-10 Applying Percents
Check It Out: Example 3 Erik is buying a blanket for $19.83. 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.
7-10 Applying Percents
Standard Lesson Quiz
Lesson Quizzes
Lesson Quiz for Student Response Systems
7-10 Applying Percents
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 $56.78. About how much would a 20% tip be?
3. The price on a book is $12.99. 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 $159.90 and sales tax is 6%, about how much will the total cost of the bike be?
about $11.50
about $25.50
about $13.50
about $150
7-10 Applying Percents
1. A pair of shoes is priced at $45.25. 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 $20 B. about $36
C. about $26 D. about $45
Lesson Quiz for Student Response Systems
7-10 Applying Percents
2. Mary and her friends ordered lunch from a restaurant. The bill came to $27.85. About how much would a home delivery charge of 15% be?
A. about $1.5 B. about $4.20
C. about $2.7 D. about $4.80
Lesson Quiz for Student Response Systems
7-10 Applying Percents
3. The price of a pen is $6.60. If sales tax is 5%, about how much will its total cost be?
A. about $6.69 B. about $7.26
C. about $6.90 D. about $7.60
Lesson Quiz for Student Response Systems
7-10 Applying Percents
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 $41.40 B. about $46.40
C. about $48.50 D. about $53.85
Lesson Quiz for Student Response Systems