# Linear and quadratic trend lines

From 1997 through 2004, the value of US exports to Mexico was as shown below. Data are in billions of dollars.

Year: 1997 1998 1999 2000

Exports: $71.4 $78.8 $86.9 $111.3

Year: 2001 2002 2003 2004

Exports: $101.3 $97.5 $97.4 $110.8

a. Fit a linear trend equation to the time series. Using this equation, determine the trend estimate for 2012.

b. Fit a quadratic equation to the time series, then use the equation to determine the trend estimate for 2012.

c. Construct a graph of the time series along with the equations fitted in parts (a) and (b). Which equation appears to better fit the data?

#### Solution Summary

A step by step solution is provided to explain the concept of linear and quadratic trend lines to the time series.