An electrical utility in a city in a South American country needs to forecast the highest temperature in the city on any day during a month. The following data reflect the highest recorded temperature (in degrees Fahrenheit) on any day during each month between June 2015 and June 2016:

Year Month High Temperature 2015 June 99.1 2015 July 102.8 Year Month High Temperature 2015 August 103.5 2015 September 104.6 2015 October 94 2015 November 96.8 2015 December 97.3 2016 January 99.7 2016 February 99.6 2016 March 101.6 2016 April 107.5 2016 May 95.9 2016 June 101.3

a. Construct a time-series plot of these data. Does it appear that a linear trend exists in the time series?

b. Calculate forecasts for each of the months in the time series. Use a smoothing constant of 0.25.

c. Calculate the MAD for the forecasts you generated in part b.

d. Construct a single exponential smoothing forecast for July 2016. Use a smoothing constant of 0.25.

Computer Software Exercises