Percent of change

1
Percent of change
On the first day of school, Wilson Middle School
had 470 students attend. On January 2 our
enrollment was 504 students. How can we describe
the increase?
2
Percent of change

• One way to describe a change in quantities is to
  use percent of change
• If the original quantity is increased we talk
  about the percent of increase
• If the original quantity is decreased we talk
  about the percent of decrease

3
Percent of Change formula
Wilson went from 470 to 504
4
Percent of Change
Do the Math!
Wilson Middle School has grown by 7.2 since the
start of the school year!
5
Percent of change
The General Assembly recently debated increasing
the minimum wage from 5.15 per hour to 8.15 per
hour. If this had passed, what would the percent
increase be?
6
Percent of change
A 58 Increase!
7
Minimum wage employees in Virginia who work 40
hours a week, 52 weeks a year, earn 10,700 a
year, 5,400 below the poverty line for a family
of three. A worker in Virginia earning minimum
wage must work 125 hours per week to afford a
modest two-bedroom apartment. That would require
working nearly 18 hours a day, 7 days a week. In
fact, the current minimum wage does not provide
enough income to enable minimum wage workers to
afford adequate housing in any area of Virginia.
The bid to raise the minimum wage in Virginia
Failed
8
In 2000 577,000 Virginians lived below the
poverty line. Today that number is 740,000
A 28 increase!
Statistics from Virginia Interfaith Center for
Public Policy
9
Percent of Change
January 2006 a gallon of regular gas costs 2.39.
Today gas is 1.92 at the Fishersville 7-11.
What is the percent of decrease.
10
Percent of Change
The price of a gallon of regular gasoline has
decreased 19.6 in the last year!
11
Percent of change
Ian had 12 girlfriends. Two broke up with him
for unknown reasons. What is the percent
decrease?
A 17 decrease in girlfriends!
12
Percent of Change
Mr. Lovell sells a necklace and earrings for 17.
He decides to lower the price to 15.50. What
is the percent decrease?
A 9 decrease
13
Percent of Change
Amanda earns an allowance of 15.00 per week.
She would like that to be raised to 25.00. What
percent increase is she asking for?
67
14
Percent of Change
Mr. Lovell went on a dietHe went from 210
pounds to 190 pounds. What percent of his weight
did he lose?
Mr. Lovell lost 9.5 or 10 of his weight.
15
Percent of change
The list price for a 4GB Ipod Nano is
199.00 Amazon is selling this Nano for
169.00 How much can you save?
A 15 savings!
16
Percent of change
When Colby was born she weighed 2.5 pounds. Now
she weighs 65 pounds. What is the percent
increase?
A 2,500 increase!!!!!!!
17
Percent of change

• Your answer is always a decimal number that needs
  to be changed to a percent.
• It is always increase or decrease over the
  original amount.
• Your answer is always a positive number

18
Homework
Page 352-353 11-22 25 - 32