You work for Segway, in the sales division of the Drift W1 (which are basically motorized roller skates). You’ve collected data on monthly sales (S) and the price of the Drift W1 (P), both in dollars, as well as the daily average summer temperature in your most popular market (T) in degrees Fahrenheit. You estimate the following regression model: S = a + bP + cT. In your regressions, you usually look for a 10%-or-better level of confidence.
a.