A help desk devoted to student software problems also receives phone calls. The number of persons that can be served in person, within one hour, is the response y . The predictor variable, x, is the number of phone calls answered.

(a) Calculate x̅, y̅ , S_xx, S_xy, and S_YY.
(b) Calculate the least squares estimates β̂₀ and β̂₁•
(c) Determine the fitted line.
(d) Use the fitted line to give a point estimate of the predicted number of persons served when 3 calls are answered.
(e) Use software to confirm your answer in Part (c).
Using R: lm(y ~ x) after x=c(0, 1,2,3,4)  and y=c(6, 7,4,2, 1)

X 0 6 12 4 7 3 2 4 1