Recall your memory on the example we discussed in class, please forecast the next $4$ quarter demand, by using multiplicative seasonal model $($trend and seasonal index$).$

b$.$ Based on the simple linear regression results, please answer the following questions: $1)$ What $\%$ of the variation in the data is explained by the model? $2)$ Is there a significant relationship between demand and quarter? $($yes or no$)[$You need to generate the regression report$]$

$*$ put all the solutions into one excel file