Bell Quiz

Objectives

• Find the percent of increase or decrease of a number

Percent of Change

• The percent of change is the ratio of the amount of change in a quantity to the original amount, expressed as a percent.

• The percent of change can be a percent of increase or a percent of decrease.

Example 1Finding the Percent of Increase or Decrease

Find the percent of change.

Number of U.S. airports in 1985: 15,161

Number of U.S. airports in 2005: 19,854

Example 2Finding the Percent of Increase or Decrease

Find the percent of change.

Number of taxicabs in the U.S. in 2001: 31,800

Number of taxicabs in the U.S. in 2002: 30,800

Lesson Practice 1

Find the percent of change.

January 2006 salary: $600/week

January 2007 salary: $630/week

Lesson Practice 2

Find the percent of change.

Number of words in the first draft of an essay: 1032

Number of words in the final draft of an essay: 774

Markup/Discount

• A markup results when a percent of increase is applied to a cost.

• A discount results when a percent of decrease is applied to a cost.

Example 3Finding Markups and Discounts

A music store marks up the price of CDs they purchases at $9.00 each by 70%. What is the markup and new price of each CD?

Example 4Finding Markups and Discounts

A bookstore is having a sale of 40% off all items. What is the discount and new price of a book that originally cost $12?

Lesson Practice 3

A shoe store marks up the price of a pair of boots that cost the store $44.00 by 45%. What is the markup and new price of the pair of boots?

Lesson Practice 4

A real estate agency is selling a house at 22% off the original cost of $344,000. What is the discount and the new price of the house?

Example 5Application: Raising Funds

In 2006, the 100 Mile BEADS Walkathon for Education, Advancements, Development, and Success raised $36,000 for girls in Africa. The organizers hope to raise $100,000 in 2007. What will be the percent of increase in the amount raised?

Lesson Practice 5

A weightlifter can lift 90 pounds. After six months he can lift 125 pounds. What is the percent of increase in the amount of weight he can lift?

Lesson Practice 6

Binders that originally sold for $4.95 each are now selling for $3.87 each. What is the percent of decrease in the price of the binders?