The data in FedReceipt represent federal receipts from 1978 through 2014, in billions of current dollars, from individual and corporate income tax, social insurance, excise tax, estate and gift tax, customs duties, and federal reserve deposits. (Data extracted from "Historical Federal Receipt and Outlay Summary," Tax Policy Center, tpc.io/1JMFKpo.)

a. Plot the series of data.

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

c. What are your forecasts of the federal receipts for 2015 and 2016?

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