Do Now 2/23/12

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Do Now 2/23/12

• Take out HW from last night.
• Exploration Activities 4 5
• Copy HW in your planner.
• Text p. 248, 7-20 all, 23-25 all
• In your notebook, put the following heading on
  the top of a new page. Section 6.4 Percent of
  Change

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Objective

• SWBAT solve problems involving percent of change

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Section 6.4 Percent of Change
Percent of change
the amount that a number increases or decreases
written as a percent
amount of change original amount
x 100
Percent of change

• If the amount goes up, it is a PERCENT of
  INCREASE.

• If the amount goes down, it is a PERCENT of
  DECREASE.

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Amount of change Original amount
x 100
Find the percent of increase or decrease
(round to the nearest tenth of a
).
Before 30 After 45
50 increase
Before 115 After 46
60 decrease
Before 116 After 146
25.9 increase
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The enrollment of Howell Middle School South in
2010-2011 was 1100 students. In the year
2011-2012 the enrollment was 1300 students.
What is the percent of increase or decrease
between the two years?
From 2010-2011 to 2011-2012 the enrollment
increased by 200, therefore our answer is a
percent of increase.
2011-2012 1300 2010-2011 1100
change 200.
0.181818
actual change original amount
200 1100
Percent of increase

18.2 increase
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There were 2.2 million computers used in public
schools in 1991 and 2 million in 1990. Find the
percent of increase.
From 1990 to 1991 the number of computers used
increased by 0.2 million or 200,000.
1991 2.2 million 1990 - 2.0 million
change 0.2 million or 200,000.
amount of change original amount
0.2 million 2 million
0.1
Percent of increase
10 increase
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Shopping and Business Applications
Manufacturer Price
Sale Price
Markup
Original Price
Retail Price
Discount
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Using a Percent of Change

• Modells buys Nike brand sneakers from the Nike
  manufacturer for 40. Modells then increases
  the price by 150. What is the retail price?

also known as a MARKUP
Retail price

Wholesale price
Amount of Increase

What is 150 of 40?


40
or (150 40)
60

40


100
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Using a Percent of Change

• You buy a shirt that is on sale for 15 off the
  original price of 25. What is the sale price?

also known as a DISCOUNT
Original price

Amount of decrease

Sale price
What is 15 of 25?


25
or (15 25)

25

3.75
21.25

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Using a Percent of Change

• Winter Wonders buys snow globes from a
  manufacturer for 9.20 each sells them at a 95
  increase in price. What is the retail price?

also known as a MARKUP
Retail price

Wholesale price
Amount of Increase

What is 95 of 9.20?


9.20
or (95 9.20)
8.74

9.20


17.94
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Using a Percent of Change

• The regular price of an MP3 player is 79.99.
  This week the MP3 player is on sale 25 off.
  What is the sale price?

also known as a DISCOUNT
Original price

Amount of decrease

Sale price
What is 25 of 79.99?


79.99
or (25 79.99)

79.99

20.00

59.99
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Using a Percent of Change

• There were about 198,000 spectators at the NCAA
  Final Four in 1995. The number of spectators
  increased by about 12 from 1995 to 2002. About
  how many spectators were there in 2002?

Spectators in 2002

Spectators in 1995

Amount of increase

198,000

(12 198,000)

198,000

23,760

221,760
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Using a Percent of Change

• In 1983, the average price of CD was 21.50.
  By 2000, the average price had decreased by
  34.8. What was the average price of a CD in
  2000?

Price in 2000

Price in 1983
x
Percent of change

21.50
x
(100 34.8)

21.50
x
65.2

14.018 14.02
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Homework
24

• Text p. 248, 7-20 all, 23-25 all