You work for Mut the Custard, a frozen custard company. You've collected data on monthly sales (S, number of regular-sized frozen custards per month) the price of your regular-sized frozen custard (P, in dollars), and the population size in the different cities in which your company operates (N, number of people; you currently only have one establishment in each city). You estimate the following regression model: S = a + bP + cN. In your regressions, you usually look for a 10%-or-better level of confidence.

e.What portion of the total variation in sales remains unexplained?

f.Mut the Custard is considering selling in a new city, where the population is 134,000, and setting its regular-sized frozen custard price at $7.49. What level of monthly sales would you expect in this new city (rounded to the nearest unit)?