A company uses a multiplicative time series model to forecast sales. The trend in sales is linear and is described by the following equation: Trend = 400 + 10 T
Where T = 1 denotes the first quarter of 2010, T = 2 denotes the second quarter of 2010 etc. The average seasonal variations are as follows
Quarter 1 2 3 4 %Variation -30 +40 +10 -20
What is the sales forecast for the third quarter of 2011?