# Percents and Parts of Change (Day 3) Saturday, September 19, 2015 We are learning to…find parts, totals and percents using proportional reasoning.

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Percents and Parts of Change (Day 3) Saturday, September 19, 2015 We are learning to…find parts, totals and percents using proportional reasoning.

Percent of Increase #% more than a number. Solve for the amount increased.  The amount increased is always the part. Add this amount to original total.

Percent of Increase Example Gabe entered a pancake eating contest. When he started training he could eat 12 pancakes. Now he can eat 50% more pancakes. How many pancakes can Gabe eat now? Increasing by 50%! First, find 50% of 12. (We’re looking for the part.) (12) This is the amount increased…not the solution. Now take the amount of increase and add this to the original total: Gabe can now eat 18 pancakes. PartsTotals x12 50 100

Percent of Decrease #% less than a number. Solve for the amount decreased.  The amount decreased is always the part. Subtract this amount from original total.

Percent of Increase Example There is a store with a sale for 25% off all items. You want to buy a shirt that originally costs \$30. What is the sale price of the shirt? Decreasing by 25%! First, find 25% of 30. (We’re looking for the part.) (30) This is the amount decreased…not the solution. Now take the amount of decrease and subtract this from the original total. The shirt costs \$22.50 after the discount. PartsTotals x30 25 100

Independent Practice Find the following amounts of increase and decrease and find the solution to the following problem situations.

Everyday examples of percent of change. Common Examples of Percent of Increase Common Examples of Percent of Decrease Sales tax on an item purchased. Finding a total bill at a restaurant including tip. Items that are on sale at a store. Population decreases.

Group Practice Pick one person to be in charge of the group…this person is in charge of reading the question and making sure everyone is in the same place at the same time. Analyze each question carefully and determine if you are increasing the total by a certain percent or decreasing the total by a certain percent.

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