Percent and Percent of Change

4-3 Percent Change

When calculating percent change

1.  DIFFERENCE  $\div$  ORIGINAL

2. THINK about the question... are the numbers in the problem increasing or decreasing?

3. Change the decimal to a PERCENT by moving two decimal spots to the right.

Percent Increase vs Percent Decrease

At noon, a tank contained 10 cm of water. After several hours, it contained 7 cm of water. What is the percent change? Was it increase or decrease?

Craig likes to collect vinyl records. Last year he had 10 records. Now he has 12 records. What is the percent change? Was it increase or decrease?

Multiple Choice

The original quantity is 5 and the new quantity is 3. What is the percent change? Is it an increase or decrease?

• 40% increase

• 40% decrease

• 0.4% increase

• 0.4% decrease

• 0.04% increase

Multiple Choice

The original quantity is 10 and the new quantity is 13. What is the percent change? Is it an increase or decrease?

• 0.3% increase

• 0.3% decrease

• 0.03% increase

• 30% decrease

• 30% increase

Multiple Choice

Carl bought an airline ticket. Two weeks ago, the cost of the flight was $300. Now the cost is $375. What is the percent increase?

• .25%

• 25%

• .40%

• 40%

Percent Error

Shaun estimated that the attendance at a college lacrosse game was 3,000. The actual attendance was 3,296. What is the percent error of Shaun's estimate? Round to the nearest whole percent.

Note:
Always divide: DIFFERENCE  $\div$   ACTUAL

Percent Error

Rihanna has a container with volume of 1.5 liters. She estimates the volume to be 2.1 liters. What is the percent error?

Note:

Always divide: DIFFERENCE  ÷ ACTUAL

Multiple Choice

The specification for the length of a bolt is 4.75 inches. A machinist makes a bolt that is 4.769 inches long. What is the percent error of the bolt's length?

• 0.4%

• 40%

• 99%

• .99%

Multiple Choice

The label on a package of bolts says each bolt has a diameter of 0.35 inches. One bolt has the diameter of 0.33 inches. What is the percent error?

• .94%

• 94%

• 5.7%

• 57%