The following data relate the sales figures of the bar in Marty and Polly Starr's small bed-and-breakfast inn in Marathon, Florida, to the number of guests registered that week: Week Guests 1 16 2 12 3 18 4 14 Bar Sales $330 270 380 300

a) Perform a linear regression that relates bar sales to guests (not to time).

b) If the forecast is for 20 guests next week, what are the sales expected to be?y