Percent Increase and Percent Decrease

Percent Increase and Decrease

A percentage that tells us how much a quantity went up or down, expressed as a percentage of the starting amount.

The original amount corresponds to 100% and the new amount corresponds to more or less than 100%, depending on whether the situation involves an increase or decrease.

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​1. We can use a double number line diagram to represent situations involving percent increase or decrease.

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​2. We can calculate the percent increase or decreases of the original amounts to identify the new amount.

​Last year, Mrs. Melder's class raised $200 to buy books for the school. This year, her class raised 22% more. How much did her class raise this year?

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​1. Find 22%of the original amount: .22 (200)

​2. Add the increase to the original amount.

Multiple Choice

Mark spent $ 178 on groceries last month. If he reduces his grocery costs by 15% next month, how much will he spend on groceries?

• $ 204.70

• $ 151.30

• $ 124.60

• $ 26.70

Multiple Choice

The original price of a pair of shoes is $29.99 and their is a mark down of 10% because the shop is having a black friday sale. What is the amount of money being taken off the original price?

• $0.29
• $2.99
• $1.99

Multiple Choice

A store marks up merchandise 40% for profit. If an item costs the store $12, what is the selling price?

• $16.80

• $4.80

• $44.80

• $19

Multiple Choice

An employee’s salary for Alar Services is $37,500. Next year, she will get an 8% increase in salary. How much is her new salary?

• $40,500

• $67,500

• $30,000

• $3,000

Multiple Choice

Mr. Hammer received a notice from his employer that the cost of his health insurance, every pay period, will increase by 8%. If the new cost will be $28.35, what was the original cost of his insurance?

• $26.08
• $26.25
• $26.81
• $27.27