Percentage Increase and Decrease with Equations

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Draw Diagram to Represent Percentage Change.

(A). Draw a diagram to represent the situation: The number of miles driven this month was a 30% decrease of the number of miles driven last month.

(B). Draw a diagram to represent the situation: The amount of paper that the copy shop used this month was a 25% increase of the amount of paper they used last month.

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Finding Percentage Change.

  •  Select whether you want a percentage increase or decrease by clicking on the appropriate box. ​
  • Click on the “Question” box if you wish to use a provided question. ​
  • Type in the amount representing 100% in the “Total” box. ​
  • Type in the “percentage change” box the required value given in the problem. ​
  • Move the slider to the right to ‘shift’ this amount to the other end of the bar. ​
  • Click on “Show change” box to highlight the new amount. ​
  • Check the “Answer” box if you used the provided question to see the answer to the problem. ​
  • Click on the “Reset” button to get a new question.

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Demonstrate Percentage Increase and Decrease.

Check the first box to start with percentage increase.

Move the slider to see percentage increase on the bar and how it is found.

Uncheck the box and check the second box to observe percentage decrease. If you run out the screen, use your mouse to enable zoom.

Move the slider to see percentage decrease on the bar and how it is calculated.

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An astronaut was exploring the moon of a distant planet, and found some glowing goo at the bottom of a very deep crater. She brought a 10 gram sample of the goo to her laboratory. She found that when the goo was exposed to light, the total amount of goo increased by 100% every hour.

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In a video game, Clare scored 50% more points than Tyler. If c is the number of points that Clare scored and is the number of points that Tyler scored, which equations are correct?