The number of pounds of steam used per month by a chemical plant is thought to be

Chapter 11, Problem 11-5

(choose chapter or problem)

The number of pounds of steam used per month by a chemical plant is thought to be related to the average ambient temperature (in F) for that month. The past years usage and temperature are shown in the following table: y i y i Month Temp. Usage/1000 Jan. 21 185.79 Feb. 24 214.47 Mar. 32 288.03 Apr. 47 424.84 May 50 454.58 June 59 539.03 Month Temp. Usage/1000 July 68 621.55 Aug. 74 675.06 Sept. 62 562.03 Oct. 50 452.93 Nov. 41 369.95 Dec. 30 273.98 (a) Assuming that a simple linear regression model is appropriate, fit the regression model relating steam usage (y) to the average temperature (x). What is the estimate of 2 ? Graph the regression line. (b) What is the estimate of expected steam usage when the average temperature is 55 F? (c) What change in mean steam usage is expected when the monthly average temperature changes by 1 F? (d) Suppose the monthly average temperature is 47 F. Calculate the fitted value of y and the corresponding residual.