The Cheyenne Hotel in Big Sky, Montana, has accumulated records of the total electrical costs of the hotel and the number of occupancy-days over the last year. An occupancy-day represents a room rented for one day. The hotel's business is highly seasonal, with peaks occurring during the ski season and in the summer.

Use the above data to calculate the equation of a cost line (Y = a + bX) using least-squares regression. See the eBook for a tutorial on using regression. Calculate the equation of a cost line by hand.

Month January February March April May June Occupancy-Days 1,736 1,904 2,356 960 360 744 2,108 2,406 840 124 720 1,364 Electrical Costs $ 4,127 $ 4,207 $ 5,083 $ 2,857 $ 1,871 $ 2,696 August September October November December 4,670 $5,148 $ 2,691 $ 1,588 $ 2,454 $ 3,529