1. Chapter 3: Solving Equations 3.7 Percent of Change

2. Percent of Increase – When a value increases from its original amount Percent of Decrease – When a value decreases from its original amount

3. Example 1 The price of a sweater decreased from $29.99 to $24.49. Find the percent of decrease.

4. Example 1a Find the percent of change if the price of a CD increases from $12.99 to $13.99. Round to the nearest percent.

5. Example 1b Find the percent of change if the CD is on sale, and its price decreases from $13.99 to $12.99. Round to the nearest percent.

6. Example 2 In 1990, there were 1330 registered alpacas in the US. By the summer of 2000, there were 29,856. What was the percent of increase in registered alpacas?

7. Example 2a The number of alpaca owners increased from 146 in 1991 to 2919 in 2000. Find the percent of increase. Round to the nearest percent.

8. Greatest Possible Error One half of a measuring unit

9. Example 3 You use a beam balance to find the mass of a rock sample for a science lab. You read the scale as 3.8 g. What is your greatest possible error?

10. Example 3a You measure a picture for the yearbook and record its height as 9 cm. What is your greatest possible error?

11. Example 4 You measure a room with dimensions of 13 ft and 7 ft. Use the greatest possible error to find the maximum and minimum possible areas.

12. Example 4a You measure a wall of your room as 8 ft high and 12 ft wide. Find the minimum and maximum possible areas of the wall.

13. Percent Error Percent error = greatest possible error measurement

14. Example 5 Suppose you measure a CD and record its diameter as 12.1 cm. Find the percent error in your measurement.

15. Example 5a You measure the length of a table as 168 inches. Find the percent error in this measurement.

16. Example 5b You measure the length of a table as 168.0 inches. Find the percent error in this measurement.

17. Example 6 A cassette case is 10.9 cm long, 6.8 cm wide, and 1.6 cm thick. Find the percent error in calculating its volume.

18. Example 6a Suppose you measured your math book and recorded the dimensions as 1 in x 9 in x 10 in. Find the percent error in calculating its volume.

19. Homework P. 171 2-38 even