Please may I get some help :)

QUESTION 3 [53] The data in the following table give quarterly sales of a product for four consecutive years. These data were considered in Assignment 01 where seasonal effects were determined using dummy variables. Now, consider using the multiplicative decomposition method to forecast sales for year 5. In the questions below, it is recommended to work by hand but the use of Excel as a spreadsheet is also accepted. Year Quarter y, 1 1 4O 52 54 65 44 53 58 68 5O 57 62 7D 62 69 73 75 OD #QJN-L-P-CONL-P-(DNL-P-QDN (3.1] Write down the general expression (before fitting to data) of the multiplicative decomposition model and indicate the meaning of each component. (5] (3.2) Compute appropriate four-point moving averages and centered moving averages for these data. (3} (3.3) Now, use the data to compute estimates of the components indicated in part (3.1 ). Show all calculation steps and summarize them into tables when appropriate. (24} (3.4] Does the model exhibit any well-defined cycle? Explain your answer in only one sentence.(4] (3.5) Compute point forecast and approximate 95% prediction interval forecast of sales for the first quarter of year 5. (12}