The following data report total, monthly U.S. book-store sales in millions of dollars from January 2016 to March 2019. (Go to https://www.census.gov/retail/index.html#mrts, find "Monthly Retail Trade Report," then select "Time Series/Trend Charts" to find the data for the total U.S. bookstore sales.)

Month	2016	2017	2018	2019
January	1508	1426	1311	1184
February	767	731	749	706
March	759	747	774	725
April	749	769	750
May	818	821	826
June	753	744	767
July	727	709	741
August	1564	1414	1404
September	1104	1037	1026
October	755	729	781
November	782	743	808
December	1296	1197	1299

d.Evaluate a seasonally adjusted trend forecasting model. What is the MAD?(Round your answers to 4 decimal places.)

month number	$ sales (millions)	period	trend	index	forecast	absolute error
1	1,508	1	?	?	?	?
2	767	2	?	?	?	?
3	759	3	?	?	?	?
4	749	4	?	?	?	?
5	818	5	?	?	?	?
6	753	6	?	?	?	?
7	727	7	?	?	?	?
8	1,564	8	?	?	?	?
9	1,104	9	?	?	?	?
10	755	10	?	?	?	?
11	782	11	?	?	?	?
12	1,296	12	?	?	?	?
1	1,426	13	?	?	?	?
2	731	14	?	?	?	?
3	747	15	?	?	?	?
4	769	16	?	?	?	?
5	821	17	?	?	?	?
6	744	18	?	?	?	?
7	709	19	?	?	?	?
8	1,414	20	?	?	?	?
9	1,037	21	?	?	?	?
10	729	22	?	?	?	?
11	743	23	?	?	?	?
12	1,197	24	?	?	?	?
1	1,311	25	?	?	?	?
2	749	26	?	?	?	?
3	774	27	?	?	?	?
4	750	28	?	?	?	?
5	827	29	?	?	?	?
6	767	30	?	?	?	?
7	741	31	?	?	?	?
8	1,404	32	?	?	?	?
9	1,026	33	?	?	?	?
10	781	34	?	?	?	?
11	808	35	?	?	?	?
12	1,299	36	?	?	?	?
1	1,184	37	?	?	?	?
2	706	38	?	?	?	?
3	725	39	?	?	?	?

MD = ?

e.What is the average monthly trend in book-store sales?(Negative amounts should be indicated by a minus sign. Round your answer to 4 decimal places.)

Average monthly trend in book-store sales ? million dollars per month.

f.What are the monthly indexes?(Round your answers to 4 decimal places.)

month	index
1	?
2	?
3	?
4	?
5	?
6	?
7	?
8	?
9	?
10	?
11	?
12	?

g.Predict book sales for the next 9 months.(Round your answers to 4 decimal places.)

year	month	forecast sales
2019	apr	?
2019	may	?
2019	june	?
2019	july	?
2019	august	?
2019	sept	?
2019	oct	?
2019	nov	?
2019	dec	?