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Math Thursday 3/1/12 1) All Pi Art posters due to me by 3/12/12 2) Do not forget Chapter 6 Re-take is due tomorrow! 3) Finish Planner 4) Begin Notes: Copy This now! Lesson 7-6 Percent of Change Objective: Students will be able to find the percent of increase or decrease.
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Math Thursday 3/1/12 1) All Pi Art posters due to me by 3/12/12 2) Do not forget Chapter 6 Re-take is due tomorrow! 3) Finish Planner 4) Begin Notes: Copy This now! Lesson 7-6 Percent of Change Objective: Students will be able to find the percent of increase or decrease. Example: If the price of popcorn at the movies was $3.00 and now it is $5.00 what is the percent of change? In order to solve you need a few “tools”. New Vocabulary: A percent of change is a ratio that compares the change in quantity to the original amount. The Equation for percent of change is: Percent of change = amount of change original amount The change is an INCREASE—if the original quantity is increased (goes up). The change is a DECREASE—if the original quantity has decreased (goes down). So, what is the percent of change for the cost of popcorn at the movies?
Lesson 7-6 Percent of change Example: If the price of popcorn at the movies was $3.00 and now it is $5.00 what is the percent of change? An Increase—The price has gone UP! First: Is the change an increase or a decrease? Always determine if you are dealing with an increase or a decrease. Second: Determine the amount of the change. The price was $3.00 now it is $5.00 so the amount of the increase is: $2.00 = amount of change or (increase) Third: Insert the values into the equation: amount of change = Percent of change original amount 67% increase 2.00 = ? 3.00 2 ÷ 3 = Round to the nearest whole percent!
Homework Practice: Pgs. 372-373 pblms 1-23 odd & 40-48 even only Find each percent of change. Round to the nearest whole percent if necessary. State whether the percent of change is an increase or a decrease. 1. 30 inches to 24 inches First: Is the change an increase or a decrease? Decrease Second: Determine the amount of the change. 30 -24 = 6 Third: Insert the values into the equation: amount of change = Percent of change original amount 0 2 6 ÷ 30 = 0.2 Is this the answer? Recall what you were asked to find! 6 6 0 30 Divide 30 60 00 Write your answer as a percent: 0.2 = 20% Decrease
2. 20.5 meters to 35.5 meters First: Is the change an increase or a decrease? increase 35.5 – 20.5 =15 Second: Determine the amount of the change. Remember: we can only subtract the smaller number from the larger. amount of change = Percent of change original amount Third: Insert the values into the equation: 0 0 0 7 3 1 15 Do not forget: the divisor cannot be a decimal. When I moved the decimal 1 place right—what did I do mathematically? Divide 20.5 15 0 0 0 0 20.5 3 5 If I multiplied the divisor by 10 what do I have to do to the dividend? 14 65 0 615 35 0 So: 15 ÷ 20.5 = 0.731 is that the answer? No, write your Answer as a percent and round to the nearest whole percent. 73% Increase
Homework Time Pages 372- 374 Pblms 1-23 odd 40-48 even