Chips Bakery has been having trouble forecasting the demand for its special high-fiber bread and would like your assistance. Data for the weekly demand, and the autocorrelations of the original data and various differences of the data, are shown in Tables P-7A-D.

a. Inspect the autocorrelation plots and suggest a tentative model for these data. How did you decide on this model? (Note: Do not difference more than necessary. Too much differencing is indicated if low lag sample autocorrelations tend to increase in magnitude.)

b. Using a computer program for ARIMA modeling, fit and check your identified model with the bread demand data.

c. Write down the equation for forecasting the demand for high-fiber bread for period