Question

Period Year 20XX-2 Sales 63 94 118 129 20XX-1 204 215 227 Quarter Spring Summer Fall Winter Spring Summer Fall Winter Spring Summer Fall Winter Spring Summer Fall Winter Quarter Seasonal Deseas. Deseas. Ave. Factor Data Forecast Forecast 204. 0 0 .90 70.0 66. 9 60.2 219.3 0.96 97.9 96.1 92.3 236.7 1.04 113.5 125.3 130.3 251.0 1.10 117.3 154.5 170.0 0.90 226.7 183.7 165.3 0.96 224.0 212.9 204.4 1.04 218.3 242.1 251.8 1.10 222.7 271.3 298.4 0.90 383.3 300.5 270.5 0.96 363.5 329.7 316.5 1.04 351.0 358.9 373.3 1.10 344.5 388.1 426.9 0.90 0.96 1.04 1.10 245 345 349 365 20XX 379 20XX+1 15 Average 227.8 Slope Intercept 29.2 37.7 1. Use the decomposition spreadsheet data above to forecast sales for winter quarter in year 20XX+1

Answer 1

Slope = 29.2

Intercept = 37.7

Deseasonalised Forecast Y = 37.7 + 29.2*t

Now,

For Winter in Year 20XX+1

t = 16

Deseasonalised Forecast = 37.7 + 29.2*16 = 504.9

and,

Seasonal Factor for For Winter in Year 20XX+1 = 1.10

Forecast = Deseasonalised Forecast*Seasonal Factor = 504.9*1.10

Forecast = 555.39

Forecast = 555.4