A manager of a home improvement store has been using the linear trend multiplicative model to predict the demand for his lawn mowers. The quarterly seasonal indices are S₁= 0.85, S₂= 0.90, S₃= 1.10, and S₄= 1.00. The linear trend equation that the manager developed is: Y_t= 15 + 6t. The following lawn mower sales have been observed for the most recent nine quarters:

Comment on the effectiveness of the forecasting method used by the manager of the store.

5 6 7 24 Quarter 4 3 8 36 38 45 Sales 18 33 40 42 32 12 10 2.