Oil prices monthly, again. Return to the oil price data of Exercise 47.

a) Find a linear model for this series.

b) Find an exponential (multiplicative) model for this series.

c) For the model of Exercise 47 and the models of parts a and

b, compute the MAPE. Which model did best? Given the plot in Exercise 47, explain why.

d) Use these methods to forecast the crude oil price for April 2007. The April price was $60.48. Which forecast was closest? Does that mean it’s the best model?