The following data report total, monthly, U.S. new car sales in millions of dollarsfrom January 2016 to March 2019. (To find the data, go to https://www.census.gov/  retail/index.html#mrts, find “Monthly Retail Trade Report,” then select “Time Series/ Trend Charts.”)

a. G raph the data.

b. Based on the graph, describe the time series pattern.

c. For this time series, why is forecasting with a seasonally adjusted trend model appropriate?

d. What is the average monthly trend in new car sales?

e. E valuate a seasonally adjusted trend forecasting model. What is the MAD?

f. What are the monthly seasonal indexes? When are new car sales the highest? When are new car sales the lowest?

g. Forecast new car sales with error for the next 9 months.

h. In your judgment, are the forecasts “good”? What disclaimer would you include with your forecast?

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Year Month 2016 2017 2018 2019 $62,058 $65,777 $69,088 $69,299 January February 67,248 67,808 68,993 69,829 March 75,579 79,892 84,914 85,562 April May 73,216 72,922 76,368 74,761 79,876 84,444 June 73,434 76,719 80,576 July August September 76,141 78,070 80,640 79,897 80,710 84,782 73,526 77,688 75,545 October 71,153 75,883 78,347 November 70,417 74,822 76,251 December 80,313 80,990 83,590