The data in Table 8 were collected by placing a temperature probe in a portable heater, removing the probe, and recording the temperature (in degrees Fahrenheit) over time (in seconds). Determine whether the relation between the temperature of the probe and time is linear.

Approach Find the least-squares regression line and determine the residuals. Plot the residuals against the explanatory variable, time. If an obvious pattern results, the linear model is not appropriate. If no pattern results, a linear model is appropriate.

Table 8 Time (seconds) Temperature (F) 1 164.5 3 163.2 5 162.0 7 160.5 9 158.6 11 156.8 13 155.1