Writing Equations for Proportional Relationships: Finding Percent Change

This video tutorial explains how to write equations to represent proportional relationships between original and final amounts by calculating the percent change. It covers the correct method to find percent change, using examples of price changes in a bike. The tutorial also addresses common misconceptions and demonstrates how to model situations with both increases and decreases in value using algebraic manipulation. Key takeaways include understanding the percent change formula and applying it to real-world scenarios.

What is the correct method to calculate the percent change between two amounts?

• Add the original and final amounts and divide by two

• Subtract the original amount from the final and divide by the final

• Subtract the final amount from the original and divide by the original

• Divide the original amount by the final amount

In the bike price example, what was the percent increase from December to June?

• 25%

• 50%

• 100%

• 75%

What is the first step in deriving an equation from the percent change proportion?

• Multiply both sides by the original amount

• Add the final amount to both sides

• Divide both sides by the percent change

• Subtract the original amount from both sides

How does the percent change calculation differ when the price decreases?

• The final amount is subtracted from the original

• The original amount is divided by the final

• The percent change is doubled

• The change is considered negative

What is the percent decrease when the bike price drops from $240 to $160?

• 66.67%

• 50%

• 33.33%

• 25%