Percentage Change

Lisa explains how to calculate percentage changes, emphasizing the importance of identifying new and old values and using multipliers. She provides examples, such as the decrease in HIV-related deaths and a car sale price, to illustrate the concept. The video concludes with practice questions and tips for distinguishing between percentage change and percentage of questions.

What is the basic formula used to calculate percentage changes?

• Old value equals new value times multiplier

• New value equals old value plus multiplier

• New value equals old value times multiplier

• Multiplier equals new value minus old value

If a multiplier starts with a decimal point, what does it indicate?

• A percentage increase

• A percentage decrease

• No change

• An error in calculation

In the example where the car's price decreased from 6,500 to 5,200, what was the percentage decrease?

• 25%

• 15%

• 20%

• 30%

What are reverse percentages used for?

• Finding the new value

• Finding the old or original value

• Calculating the multiplier

• Determining the percentage increase

What should you do if one value isn't clearly older or newer than the other?

• Assume it's a finding a percentage question

• Assume it's a percentage change question

• Use the average of the two values

• Ignore the question