orignal amount This is your formula for finding percent of change这是你原来的量的变化发现率公式！.pptVIP

Percent of Change Tuesday, January 6, 2009 Lesson Objectives Real-Life Connection What things in everyday life are described as % increases or % decreases? What things in everyday life are described as percent increases or decreases? Fuel prices (example: The cost of gas might increase by 10% over a major holiday weekend) Other product prices (example: You might go shopping and find a sweater that’s 20% off) The stock market (example: You may read in the newspaper that a corporation’s shares have risen 1.8%) Any increase or decrease can be represented as a percent!  Vocabulary A percent of change is a ratio It compares the change in quantity to the original amount  change in quantity  __________________ original amount This is your formula for finding percent of change!  change in quantity  _______________ original amount Vocabulary If the original amount goes up, or increases, then it is a percent of increase If the original amount goes down, or decreases, then it is a percent of decrease Example 1 Let’s say you are shopping for a jacket The original cost of the jacket is $50 The jacket is on sale for $35 Is this situation an increase or decrease? Example 1 Use the percent of change formula to find the percent of decrease in the cost Example 1 – step one: apply the formula change in cost = $50 – 35 = $ 15 ___________ _______ ____ original cost $50 $50 Example 1 – step two: convert the ratio to a percent $15 15 30 ___ or ___ = ___ = 30% $50 50 100 Example 1 – solution The price of the jacket was decreased by 30% In other words, the jacket was on sale for 30% off Example 2 Rita weighed 120 pounds on Thanksgiving. On New Year’s Day, she weighed 130 pounds. Find the percent of change in Rita’s weight from Thanksgiving to New Year’s Day and state whether it is