Gross domestic product (GDP) is a major indicator of a nation's overall economic activity. It consists of personal consumption expenditures, gross domestic investment, net exports of goods and services, and government consumption expenditures. The file GDP contains the GDP (in billions of current dollars) for the United States from 1980 to 2014. (Data extracted from Bureau of Economic Analysis, U.S. Department of Commerce, www.bea .gov.)

a. Plot the data.

b. Compute a linear trend forecasting equation and plot the trend line.

c. What are your forecasts for 2015 and 2016?

d. What conclusions can you reach concerning the trend in GDP?