Answer:
Quarter 1, Sales 88. seasonal relatives 1.1
Deseasonalized = 88 / 1.1 = 80
Quarter 2, Sales 99. seasonal relatives 0.99
Deseasonalized = 99 / 0.99 = 100
Trend = 80+(100-80) = 100
Reseasonalized = 100*0.99 = 99
Quarter 3, Sales 108, seasonal relatives 0.9
Deseasonalized = 108 / 0.9 = 120
Trend = 1000+ (120-100) = 120
Reseasonalized = 1120*0.9 = 108
Quarter 4, Sales 141.4, seasonal relatives 1.01
Deseasonalized = 141.1 / 1.01 = 140
Trend = 120+ (140-120) = 140
Reseasonalized = 140*1.01 = 141.4
Now to get the Naive trend forecast for the next year first quarter, we say
140 + (140 - 120) = 160
Also to get the Re-seasonalized forecast for the next year first quarter, we say
160*1.1 = 176