40 In addition to his day job as an engineer, Luis Garcia runs a small ethnic grocery store. The shop stocks food items from southeast Asian countries and caters to the large population of people from this region who live in Luis’s community. Luis wants to develop a quantitative model to forecast sales. His sales data

(in thousands) for the past 16 quarters are as shown in the Table for Problem 40.

Table for Problem 40 QUARTER YEAR 1 YEAR 2 YEAR 3 YEAR 4 Quarter 1 $42.9 $43.8 $49.0 $51.3 Quarter 2 $48.5 $50.3 $54.2 $58.2 Quarter 3 $54.1 $57.8 $59.3 $62.9 Quarter 4 $74.1 $79.8 $83.3 $88.5 Develop a multiplicative decomposition model for Luis’s sales data. Use the model to forecast revenues for year 4. Comment on the validity of the model.