Question

The table below shows monthly beer sales at Gordon’s Liquor Store in 2017.

Month	Sales
Jan	900
Feb	725
Mar	1000
Apr	800
May	750
Jun	1200
Jul	1000
Aug	1100
Sep	1250
Oct	1050
Nov	1400
Dec	1600
Jan

Forecast beer sales needed for January 2018 using an exponential smoothing method

50. α = 0.2, α = 0.4 and α = 0.9
50. Plot the data and identify the method to forecast the beer sales

Answer 1

	At	Ft	Ft	Ft
Month	Sales	a=0.2	a=0.4	a=0.9
Jan	900	900	900	900
Feb	725	900	900	900
Mar	1000	865	830	742.5
Apr	800	892	898	974.25
May	750	873.6	858.8	817.425
Jun	1200	848.88	815.28	756.7425
Jul	1000	919.104	969.168	1155.674
Aug	1100	935.2832	981.5008	1015.567
Sep	1250	968.2266	1028.9	1091.557
Oct	1050	1024.581	1117.34	1234.156
Nov	1400	1029.665	1090.404	1068.416
Dec	1600	1103.732	1214.243	1366.842
Jan-18		1202.986	1368.546	1576.684

Formula sheet

	At	Ft	Ft	Ft
Month	Sales	a=0.2	a=0.4	a=0.9
Jan	900	=B3	=C3	=D3
Feb	725	=0.2*C3+(1-0.2)*C3	=0.4*D3+(1-0.4)*D3	=0.9*E3+(1-0.9)*E3
Mar	1000	=0.2*B4+(1-0.2)*C4	=0.4*B4+(1-0.4)*D4	=0.9*B4+(1-0.9)*E4
Apr	800	=0.2*B5+(1-0.2)*C5	=0.4*B5+(1-0.4)*D5	=0.9*B5+(1-0.9)*E5
May	750	=0.2*B6+(1-0.2)*C6	=0.4*B6+(1-0.4)*D6	=0.9*B6+(1-0.9)*E6
Jun	1200	=0.2*B7+(1-0.2)*C7	=0.4*B7+(1-0.4)*D7	=0.9*B7+(1-0.9)*E7
Jul	1000	=0.2*B8+(1-0.2)*C8	=0.4*B8+(1-0.4)*D8	=0.9*B8+(1-0.9)*E8
Aug	1100	=0.2*B9+(1-0.2)*C9	=0.4*B9+(1-0.4)*D9	=0.9*B9+(1-0.9)*E9
Sep	1250	=0.2*B10+(1-0.2)*C10	=0.4*B10+(1-0.4)*D10	=0.9*B10+(1-0.9)*E10
Oct	1050	=0.2*B11+(1-0.2)*C11	=0.4*B11+(1-0.4)*D11	=0.9*B11+(1-0.9)*E11
Nov	1400	=0.2*B12+(1-0.2)*C12	=0.4*B12+(1-0.4)*D12	=0.9*B12+(1-0.9)*E12
Dec	1600	=0.2*B13+(1-0.2)*C13	=0.4*B13+(1-0.4)*D13	=0.9*B13+(1-0.9)*E13
43101		=0.2*B14+(1-0.2)*C14	=0.4*B14+(1-0.4)*D14	=0.9*B14+(1-0.9)*E14

Graph