The file P2_57.XLS contains three years (1991-1993) of sales data for the Sky’s the Limit Women’s Apparel store. Each observation represents sales during a 4-week period. Thus the first observation is sales during the first 4 weeks of 1991, and so on. a Does there appear to be any trend in sales? b Do sales appear to be seasonal? If so, discuss the nature of the seasonality.