The facility manager at a pharmaceutical company wants to build a regression model to forecast monthly electricity cost. Three main variables are thought to be related to the electricity cost (Cost in $): (1) the average outdoor temperature (in degrees Fahrenheit), (2) the number of working days per month, and (3) the tons of product produced. The accompanying data file shows the results for the past 12 months.

Cost	Temp	Days	Tons
24100	26	24	80
23700	32	21	73
26800	46	24	90
27400	61	23	69
30200	66	24	75
31500	73	23	80
30100	81	24	82
29500	85	24	80
26800	76	23	78
27500	61	24	79
28900	51	23	75
26000	39	22	69

Use excel:

a. For each independent variable, discuss whether it is likely to have a positive or negative relationship with the monthly electricity cost. Justify your answer. (Use excel) b. Estimate the sample regression equation for the regression model using all three independent variables. Write the estimated regression model in equation form. (Use excel) c. What is the predicted electricity cost in a month during which the average outdoor temperature is 65 degrees, there are 23 working days, and 76 tons are produced?(Use excel)