The Consumer Price Index (CPI) is calculated by the U.S. Department of Labor. It is a measure of the relative price of a typical market basket of goods in the given year. The percentage increase in the CPI from one year to the next gives one measure of the annual rate of inflation. The following table shows the CPI in December of the given year. Here, C represents the Consumer Price Index, and t is the time in years since December 2008. In the figure on the left, we have plotted the data, and in the figure on the right, we have added the trend line, which is given by C = 3.86t + 212.12. Determine the slope of the trend line. Explain in practical terms the meaning of the slope.

• The CPI increases by approximately 212.12 units each year.
• The CPI decreases by approximately 212.12 units each year.
• The CPI increases by 1 unit approximately every 3.86 years.
• The CPI increases by approximately 3.86 units each year.
• The CPI decreases by approximately 3.86 units each year.