21. Data in the Excel File Microprocessor Data shows the demand for one type of chip used in industrial equipment from a small manufacturer.

a. Construct a chart of the data. What appears to happen when a new chip is introduced?

b. Develop a causal regression model to forecast demand that includes both time and the introduction of a new chip as explanatory variables.

c. What would the forecast be for the next month if a new chip is introduced?

What would it be if a new chip is not introduced?