Help on solving questions 9 and 10 please. The answers I am getting for the MAE, MSE and MAPE are not correct. Solutions for these problems are greatly appreciated. Thank you

Consider the following quarterly time series of sales of a particular store (See the Excel file Sales in Canvas): Year 1 Year 2 Year 3 1 923 1112 1243 2 1056 1156 1301 3 1124 1124 1254 4 992 1078 1198 7. Construct a time series plot. What type of pattern exists in the data? 8. Use a regression model that will account for seasonal effects and linear trend (seasonality with trend) in the data. Include dummy variables to capture seasonal effects, as Qtrl = 1 if quarter 1, 0 otherwise; Qtr2 = 1 if quarter 2, 0 otherwise, etc...The overall estimated model should be as follows: gt = bo + by (Qtrl) + ba(Qtr2) + by (Qtr3) + byt 9. Compute the MAE, MSE, and MAPE of the model in #8. 10. Based on your model in #8, compute the quarterly forecasts for Year 4