The following data report total, monthly U.S. gasoline sales in millions of dollars from January 2017 to December 2018. (To find the data, go to the site https://www.census.gov/retail/index.html#mrts, find "Monthly Retail Trade Report," then select "Time Series/Trend Charts.")

Year	Month	Sales
($ millions)
2017	Jan	34,730
2017	Feb	33,072
2017	Mar	37,722
2017	Apr	38,073
2017	May	39,839
2017	Jun	39,109
2017	Jul	38,897
2017	Aug	40,317
2017	Sep	40,446
2017	Oct	40,817
2017	Nov	39,286
2017	Dec	39,146
2018	Jan	38,323
2018	Feb	36,477
2018	Mar	41,748
2018	Apr	42,209
2018	May	47,149
2018	Jun	46,646
2018	Jul	47,091
2018	Aug	47,933
2018	Sep	44,685
2018	Oct	47,442
2018	Nov	42,339
2018	Dec	38,726

d. Evaluate a seasonally adjusted trend forecasting model. What is the MAD? (Round your answers to 3 decimal places.)

Period	Month-Year	Year	Month	Sales ($ millions)	Trend	Index	Forecast	Absolute Error
1	Jan-17	2017	1	34,730
2	Feb-17	2017	2	33,072
3	Mar-17	2017	3	37,722
4	Apr-17	2017	4	38,073
5	May-17	2017	5	39,839
6	Jun-17	2017	6	39,109
7	Jul-17	2017	7	38,897
8	Aug-17	2017	8	40,317
9	Sep-17	2017	9	40,446
10	Oct-17	2017	10	40,817
11	Nov-17	2017	11	39,286
12	Dec-17	2017	12	39,146
13	Jan-18	2018	1	38,323
14	Feb-18	2018	2	36,477
15	Mar-18	2018	3	41,748
16	Apr-18	2018	4	42,209
17	May-18	2018	5	47,149
18	Jun-18	2018	6	46,646
19	Jul-18	2018	7	47,091
20	Aug-18	2018	8	47,933
21	Sep-18	2018	9	44,685
22	Oct-18	2018	10	47,442
23	Nov-18	2018	11	42,339
24	Dec-18	2018	12	38,726
							MAD =

e. What are the monthly indexes? (Round your answers to 3 decimal places.)

Month	Index
1
2
3
4
5
6
7
8
9
10
11
12

f. Forecast sales for January, February, March, and April of 2019. (Round your answers to 2 decimal places.)

	Forecasted Sales
Period 25 Sales	___ million
Period 26 Sales	___ million
Period 27 Sales	___ million
Period 28 Sales	___ million