1. An international business uses a simple linear regression model to establish the relationship between its sales (Y) and the volume of advertisements (X).
Given the following 10 sets of data (y1, x1),...(y10, x10), where yi is the sales in the ith month, and xi is the number of advertisements in the ith month. According to the information:
10 sales data y1,..., y10, the average value of yi is 130, and the variance is 1748. The number of advertisements for 10 advertisements is x1,...,x10, and the average value of xi is 14. In addition, the sales data y1,...,y10, and the advertisement frequency data x1,...,x10, the covariance is 316.
Using the least squares method, the estimated regression relationship is Y = 60 + 5X.
(1) If the sales in the third month are y3 = 88 and the volume of advertisements performed is x3 = 8, please try to calculate the fitted value and residual value of this month's sales. (5 points)