(a) Make an Excel graph of the data on U.S. online advertising spending. (b) Discuss the underlyingcauses that might explain the trend or pattern. (c) Use Excel, MegaStat, or MINITAB to fitthree trends (linear, quadratic, exponential) to the time-series. (d) Which trend model do you thinkis best to make forecasts for the next 3 years? Why? (e) Use each of the three fitted trend equationsto make a numerical forecast for 2007. How similar are the three models’ forecasts?