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Common Core Standard: 7.RP.A.3

Sample problem percent increase. John got a raise at work from $5.00 an hour to

$ 6.00 dollars an hour. What percent increase is his raise?

Step 1. Use the formula:

6-5/5 x 100

1/5 x 100

Step 2. Reduce the fraction, and divide the numerator ( top number) by the denominator ( bottom number) then multiply by 100 to calculate the percent.

1/5 = .20

.20 x 100 = 20%

Example "A difference Problem"

From year 2010 to year 2011 a school's population increased from 1000 students to 1200 students. What percent increase was there from 2010 to 2011 in student population?

Step 1. Find the difference between the two amounts ?

1200 -1000 = 200

Step 2. Plug your numbers into the percent increase formula. 200

Step 3. Reduce 200

Step 4. Divide the numerator by the denominator and multiple by 100

Bob bought a bike for $40, and he sold it for $60. He made a profit of what percent?

Drew’s followers on FB increased from 200 followers to 600 followers. By what percent did his number of followers increase?

A cell phone was reduced from $120.00 to $80. The phone was marked down what percent?

Video answers: Percent increase and decrease word problems

60-40 = $20 = profit

Use part/whole

20/40 = .50 x100 =50%

120-80 = 40 amount of reduction

Use part/whole

40/120 = .3375 x100 = 33.75 % reduction

600 -200 =400 number of new followers

400/200 = 2.00 x 100= 200%

How do you figure percent increase or decrease? Sometimes these problems are called " a difference problem." Percent increase or percent decrease problems calculate the percent change that occurs. For example, if John normally receives $5.00 an hour, but received a raise, and now receives $7.00 an hour, what is his percentage raise? In order to calculate the percent increase, you take the difference between the original amount and the new amount, and the divide this amount by the original amount. Next, in order to calculate the percent you multiply the answer by 100. These steps are summarized in the following formula.

What about a percentage decrease?

If you plug the information into the percent change formula, and get a negative number you have a percent decrease.

Example problem decrease decrease, John’s company is not doing well, and he must reduce all of his workers’ wages by $2. If each worker currently makes $5.00 an hour, what is their percent decrease if their wage is changed to $3.00 dollars an hour?

Step 1. Subtract the New Value- Old Value

3-5= -2 The workers wage is now $3.00, and their old wage was $5.00

Step 2. Next divide this amount by the old value

-2/5= -.40

Step 3. Now multiply by 100 in order to get a percentage