Transcript 6-3 - My CCSD

6-3 Estimate with Percents
Warm Up
Problem of the Day
Lesson Presentation
Course 2
6-3 Estimate with Percents
Homework pg. 338 #11-19 and29-32
Warm Up
Write each percent as a fraction and as a
decimal.
3, 0.75
1. 75% 4
January 26, 2012
1 , 0.1
2. 10% 10
8 , 0.32
3. 32% 25
17 , 0.17
4. 17% 100
Course 2
6-3 Estimate with Percents
EQ: When is the situation to
use estimate of a percent
or when does it need to be
exact.
Power Point Lesson 6:3
KIN Page 147-148
Course 2
6-3 Estimate with Percents
Learn to estimate 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
10%
20%
25%
Fraction
1
10
1
5
1
4
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1
33 3 %
50%
2
663 %
1
3
1
2
2
3
6-3 Estimate with Percents
Additional Example 1: Using Fractions to Estimate
Percents
Use a fraction to estimate 27% of 63.
Think: 27% is about 25% and
1
25% is equivalent to .
4
 1 · 60 Change 63 to a compatible
4
number.
 15
Multiply.
27% of 63 is about 15.
27% of 63  1 · 63
4
Remember!
Compatible numbers are close to the numbers in the problem
and help you use mental math to find a solution.
Course 2
6-3 Estimate with Percents
Check It Out: Example 1
Use a fraction to estimate 48% of 91.
48% of 91  1 · 91
2
Think: 48% is about 50% and
1
50% is equivalent to .
2
 1 · 90
2
Change 91 to a compatible
number.
 45
Multiply.
48% of 91 is about 45.
Course 2
6-3 Estimate with Percents
Additional Example 2: Consumer Math Application
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?
First find the discount price for 2 t-shirts at Good T’s.
50% of $9.99 = 1 · $9.99 Think: 50% is equivalent to 1 .
2
2
1 · $10 Change $9.99 to a

compatible number.
2
Multiply.
 $5
The second shirt cost approximately $5. Since $10
+ $5 = $15, the 2 T-shirts for $15 at Good-T’s is
the better deal.
Course 2
6-3 Insert
Lesson
Here
Estimate
with Title
Percents
Check It Out: Example 2
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?
First find the discount on the notebook at Billy’s Office Supply.
25% of $9.75 = 1 · $9.75
4
1 · $10

4
 $2.50
Think: 25% is equivalent to 1 .
4
Change $9.75 to a compatible
number.
Multiply.
The discount is approximately $2.50. Since $10 - $2.50 =
$7.50, the notebook from K’s Office Supply Store is the
better deal.
Course 2
6-3 Estimate with Percents
Additional Example 3A: Estimating with Simple
Percents
Use 1% or 10% to estimate the percent of
each number.
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% equals 4 · 1%.
4% of 18 is about 0.8.
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6-3 Estimate with Percents
Additional Example 3B: Estimating with Simple
Percents
Use 1% or 10% to estimate the percent of
each number.
29% of 80
29% is about 30, so find 30% of 80.
10% of 80 = 80.
.
30% of 80 = 3 · 8.0 = 24.0 30% equals 3 · 10%.
29% of 80 is about 24.
Course 2
6-3 Estimate with Percents
Check It Out: Example 3A
Use 1% or 10% to estimate the percent of
each number.
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% equals 5 · 1%.
5% of 14 is about 0.75.
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6-3 Estimate with Percents
Additional Example 4: Consumer Math Application
Tim spent $58 on dinner for his family. About
how much money should he leave for a 15%
tip?
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
Think: 15% is 10% + 5%.
1
5% is 2 of 10% so divide
$6 by 2.
Add the 10% and 5%
estimates.
Tim should leave about $9 for a 15% tip.
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6-3 Estimate with Percents
Check It Out: Example 4
Amanda spent $12 on a hair cut. About how
much money should she leave for a 15% tip?
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
Think: 15% is 10% + 5%.
1
5% is 2 of 10% so divide
$1 by 2.
Add the 10% and 5%
estimates.
Amanda should leave about $1.50 for a 15% tip.
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6-3 Estimate
Insert Lesson
with Percents
Title Here
Lesson Quiz
1. Use a fraction to estimate 48% of 72. 36
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? The café
Estimate the percent of each number.
3. 4% of 220
8.8
4. 19% of 75
15
$7
5. Mr. and Mrs. Dargen spend $46.25 on a meal.
About how much should they leave for a 15% tip?
Course 2