Each month, the owner of Café Gardens restaurant records y = monthly total sales receipts and x = amount spent that month on advertising, both in thousands of dollars. For the first four months of operation, the observations are as shown in the table. The correlation equals 0.857.
a. Find the mean and standard deviation for each variable.
b. Using the formulas for the slope and the y -intercept or software, find the regression line.
c. The se of the slope estimate is 0.364. Test the null hypothesis that these variables are independent, using a significance level of 0.05.