Repeated Percentage Change Challenges
Explore various scenarios involving repeated percentage changes such as sales, investments, savings, and value depreciation. Test your math skills with calculations, understanding multipliers, predicting outcomes, and debunking misconceptions. Challenge yourself with practical examples to master the concept of repeated percentage changes.
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Presentation Transcript
Repeated percentage change In a sale, all the prices are reduced by 25%. Julie sees a jacket that cost 32 before the sale. How much does it cost in the sale? Show your calculations.
Repeated percentage change In the second week of the sale, the prices are reduced by 25% of the previous week s price. In the third week of the sale, the prices are again reduced by 25% of the previous week s price. In the fourth week of the sale, the prices are again reduced by 25% of the previous week s price. Julie thinks this will mean that the prices will be reduced to 0 after the four reductions because 4 x 25% = 100%. Explain why Julie is wrong.
Repeated percentage change If Julie is able to buy her jacket after the four reductions, how much will she have to pay?
Repeated percentage change 50 is invested in a high interest account at 7% for 5 years. How much money will be in the account at the end? Method 1: 50 x 1.07 = 53.50 x 1.07 = 57.25 x 1.07 = 61.26 x 1.07 = 65.55 x 1.07 =
Repeated percentage change Alice invests 50 in a high interest account at 7% for 5 years. How much money will she have at the end? Method 2: 50 x 1.07 x 1.07 x 1.07 x 1.07 x 1.07 50 x 1.075 = 70.13
Using boxes Number of years X1.05 8 200 Percentage increase or decrease Initial amount
Repeated Percentage Change 1. Craig puts 240 into a savings account. Each year the savings earn interest at 6% of the amount at the start of the year. What will his savings be worth after 3 years? Give your answer to the nearest penny. 2. Each year a car loses value by 11% of its value at the start of the year. If it was worth 8000 when it was new, what will it be worth after 2 years? 3. A population of bacteria is estimated to increase by 12% every 24 hours. T The population was 2000 at midnight on Friday. What was the population (to the nearest whole number) by midnight the following Wednesday?
Repeated Percentage Change Challenge A washing machine is reduced by 20% in the first week of the sale and then reduced by a further 25% in the second week. What is the total percentage reduction? How did you work it out? Clue: What are the multipliers? What happens if you combine them?
