6-3 Estimate with Percents

Course 2

Warm UpWarm Up

Problem of the DayProblem of the Day

Lesson PresentationLesson Presentation

Homework pg. 338 #11-19 and29-32Warm UpWrite each percent as a fraction and as a decimal.

1. 75% January 26, 2012

2. 10%

3. 32%

4. 17%

34

, 0.75

Course 2

6-3 Estimate with Percents

, 0.1 10 1

, 0.32 25 8

, 0.17 10017

EQ: When is the situation to use estimate of a percent or when does it need to be exact.

Course 2

6-3 Estimate with Percents

Power Point Lesson 6:3 KIN Page 147-148

Learn to estimate percents.

Course 2

6-3 Estimate with Percents

Course 2

6-3 Estimate with Percents

The table shows common percents and their fraction equivalents. You can use fractions to estimate the percent of a number by choosing a fraction that is close to a given percent.

Percent

Fraction

10% 20% 25% 50%33 %13 66 %2

3

15

14

13

12

23

110

Use a fraction to estimate 27% of 63.

Additional Example 1: Using Fractions to Estimate Percents

Course 2

6-3 Estimate with Percents

27% of 63 14

· 63

14

· 60

1527% of 63 is about 15.

Compatible numbers are close to the numbers in the problem and help you use mental math to find a solution.

Remember!

Think: 27% is about 25% and

25% is equivalent to .14

Change 63 to a compatible number.

Multiply.

Use a fraction to estimate 48% of 91.

Check It Out: Example 1

Course 2

6-3 Estimate with Percents

48% of 91 12

· 91

12

· 90

45

48% of 91 is about 45.

Think: 48% is about 50% and

50% is equivalent to .12

Change 91 to a compatible number.

Multiply.

Tara’s T’s is offering 2 T-shirts for $16, while Good-T’s is running their buy one for $9.99, get one for half price sale. Which store offers the better deal?

Additional Example 2: Consumer Math Application

Course 2

6-3 Estimate with Percents

First find the discount price for 2 t-shirts at Good T’s.

50% of $9.99 = 12

· $9.99

12

· $10

$5The second shirt cost approximately $5. Since $10 + $5 = $15, the 2 T-shirts for $15 at Good-T’s is the better deal.

Think: 50% is equivalent to .12

Change $9.99 to a compatible number.

Multiply.

Check It Out: Example 2

Insert Lesson Title Here

Course 2

6-3 Estimate with Percents

First find the discount on the notebook at Billy’s Office Supply.

25% of $9.75 = 14

· $9.75

14

· $10

$2.50The discount is approximately $2.50. Since $10 - $2.50 = $7.50, the notebook from K’s Office Supply Store is the better deal.

Think: 25% is equivalent to .14

Change $9.75 to a compatiblenumber.

Multiply.

Billy’s Office Supply Store is offering 25% off a leather notebook, originally priced at $9.75. K’s Office Supply Store offers the same notebook, not on sale, at $7.00. Which store offers the better deal?

Use 1% or 10% to estimate the percent of each number.

Additional Example 3A: Estimating with Simple Percents

Course 2

6-3 Estimate with Percents

4% of 18

18 is about 20, so find 4% of 20.

1% of 20 = 20.

4% of 20 = 4 · 0.2 = 0.8

4% of 18 is about 0.8.

4% equals 4 · 1%.

.

Use 1% or 10% to estimate the percent of each number.

Additional Example 3B: Estimating with Simple Percents

Course 2

6-3 Estimate with Percents

29% of 80

29% is about 30, so find 30% of 80.

10% of 80 = 80.

30% of 80 = 3 · 8.0 = 24.0

29% of 80 is about 24.

30% equals 3 · 10%.

.

Use 1% or 10% to estimate the percent of each number.

Check It Out: Example 3A

Course 2

6-3 Estimate with Percents

5% of 14

14 is about 15, so find 5% of 15.

1% of 15 = 15.

5% of 15 = 5 · 0.15 = 0.75

5% of 14 is about 0.75.

5% equals 5 · 1%.

.

Tim spent $58 on dinner for his family. About how much money should he leave for a 15% tip?

Additional Example 4: Consumer Math Application

Course 2

6-3 Estimate with Percents

Since $58 is about $60, find 15% of $60.

15% = 10% + 5%

10% of $60 = $6

5% of $60 = $6 ÷ 2 = $3

$6 + $3 = $9

Tim should leave about $9 for a 15% tip.

Think: 15% is 10% + 5%.

5% is of 10% so divide $6 by 2.

12

Add the 10% and 5% estimates.

Amanda spent $12 on a hair cut. About how much money should she leave for a 15% tip?

Check It Out: Example 4

Course 2

6-3 Estimate with Percents

Since $12 is about $10, find 15% of $10.

15% = 10% + 5%

10% of $10 = $1

5% of $10 = $1 ÷ 2 = $0.50

$1 + $0.50 = $1.50

Amanda should leave about $1.50 for a 15% tip.

Think: 15% is 10% + 5%.

5% is of 10% so divide $1 by 2.

12

Add the 10% and 5% estimates.

Lesson Quiz1. Use a fraction to estimate 48% of 72.

2. A café is offering 10% off the $4.99 lunch. If a diner is offering the same lunch for $4.59, which is offering the better deal?

Estimate the percent of each number.

3. 4% of 220

4. 19% of 75

5. Mr. and Mrs. Dargen spend $46.25 on a meal. About how much should they leave for a 15% tip?

The café

36

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8.8

15

Course 2

6-3 Estimate with Percents

$7