8 -10 Using Percents Warm Up Problem of

8 -10 Using Percents Warm Up Problem of the Day Lesson Presentation Course 1

8 -10 Using Percents Warm Up Find the percent of each number. 1. 2. 3. 4. Course 1 75% of 300 93% of 56 32% of 128 9% of 60 225 52. 08 40. 96 5. 4

8 -10 Using Percents Problem of the Day A chessboard is 8 squares wide by 8 squares long. Each player has 8 pawns, 1 king, and 7 other pieces. At the start of a game, all the pieces are on the board, 1 piece per square. What percent of the total number of squares have a chess piece? 50% Course 1

8 -10 Using Percents Learn to solve percent problems that involve discounts, tips, and sales tax. Course 1

8 -10 Insert Lesson Title Here Using Percents Vocabulary discount tip sales tax Course 1

8 -10 Using Percents Discounts Tips Sales tax Course 1 Common Uses of Percents A discount is an amount that is subtracted from the regular price of an item. discount = price • discount rate total cost = price – discount A tip is an amount added to a bill for service. tip = bill • tip rate total cost = bill + tip Sales tax is an amount added to the price of an item. sales tax = price • sales tax rate total cost = price + sales tax

8 -10 Using 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. Course 1

8 -10 Using Percents Remember! To multiply by 0. 10, move the decimal point one place left. Course 1

8 -10 Using Percents Try This: 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. Course 1

8 -10 Using 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 onehalf of 10% of the number. Course 1

8 -10 Using 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% 10% of $8 = 0. 10 • $8 = $0. 80 Step 3: 5% = 10% ÷ 2 = $0. 80 ÷ 2 = $0. 40 Step 4: 15% = 10% + 5%. = $0. 80 + $0. 40 = $1. 20 Ben should leave about $1. 20 as a tip. Course 1

8 -10 Using Percents Try This: 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% 10% of $12 = 0. 10 • $12 = $1. 20 Step 3: 5% = 10% ÷ 2 = $1. 20 ÷ 2 = $0. 60 Step 4: 15% = 10% + 5%. = $1. 20 + $0. 60 = $1. 80 Lita should leave about $1. 80 as a tip. Course 1

8 -10 Using 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. Course 1

8 -10 Using Percents Try This: 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. Course 1

8 -10 Using Percents Insert Lesson Title Here 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? About $25. 50 2. The bill for a family dinner comes to $56. 78. About how much would a 20% tip be? About $11. 50 3. The price on a book is $12. 99. If sales tax is 4%, about how much will its total cost be? About $13. 50 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 $150 Course 1