The following data represents the monthly electrical expense for an office space over the past three years. You are considering opening a new business in this office space and are preparing an expected budget for your business plan.

Month	Year 1	Year 2	Year 3
January	170	180	195
February	180	205	210
March	205	215	230
April	230	245	280
May	240	265	290
June	315	330	390
July	360	400	420
August	290	335	330
September	240	260	290
October	240	270	295
November	230	255	280
December	195	220	250

a) Using overall average develop a seasonal index for each month and report your results.

b) Using centered moving average develop a seasonal index for each month and report your results.

c) Using the centered moving average data to predict the electric bill for each month of next year. Report your results.

d) Use the data below to predict the electric bill for each month of next year using linear trend and the seasonal index from the overall average. Report your results.

Month	Year 1	Year 2	Year 3
January	247.852	262.431	284.3
February	240.378	273.764	280.441
March	250.599	262.824	281.16
April	242.058	257.845	294.68
May	239.874	264.861	289.848
June	241.83	253.345	299.408
July	242.415	269.35	282.818
August	241.287	278.728	274.568
September	241.392	261.508	291.682
October	236.894	266.506	291.183
November	238.894	264.861	290.828
December	232.998	262.87	298.716

e) Compare the results between your predictions in parts c and d. Which set of predictions would you use? Explain your answer.