The following table reports the Consumer Price Index for the Los Angeles area on a monthly basis from January 1998 to Decemeber 2000 (Base year = 1982-1984).Eliminating the data for 2000, use Excel to forecast the index for all of 2000 using a three ? and six month average. Which provides a better forecast 2000 using the data provided? How do I set up the calcuations for these columns. In other words what is the formula look like?