A researcher collects the data shown at the left and concludes that there is a significant relationship between the amount of radio advertising time (in minutes per week) and the weekly sales of a product (in hundreds of dollars). Find the standard error of estimate. Use the regression equation

ŷ = 1.405x + 7.311

a. Use a table to calculate the sum of the squared differences of each observed y-value and the corresponding predicted y-value.

b. Identify the number n of pairs of data.

c. Calculate se.

d. Interpret the results.

Radio ad time, x        Weekly sales, y

15 …………………………   26

20 …………………………   32

20 …………………………   38

30 …………………………   56

40 …………………………   54

45 …………………………   78

50 …………………………   80

60 …………………………   88