The file P14_26.xlsx contains the monthly number of airline tickets sold by the CareFree Travel Agency.

a. Create a time series chart of the data. Based on what you see, which of the exponential smoothing models do you think will provide the best forecasting model? Why?

b. Use simple exponential smoothing to forecast these data, using a smoothing constant of 0.1.

c. Repeat part b, but search for the smoothing constant that makes RMSE as small as possible. Does it make much of an improvement over the model in part b?