i$.$ The reason for deseasonalizing a sales series is to remove trend and cyclical fluctuations so that we can study seasonal fluctuations.

ii$.$ Using the ratio$-$to$-$moving$-$average method, dividing the actual sales for a month by the typical seasonal for that month results in a figure that includes only trend, cycle and irregular fluctuations. This procedure is called deseasonalizing the sales.

iii. Knowing the seasonal pattern in the form of indexes allows the retailer to deseasonalize sales. This is accomplished by dividing the actual sales for a month by the typical index for that month.