The following table summarizes sales by day of the week at a convenience store operated by a major domestic gasoline retailer. The data cover about one year, with 52 values for each day of the week....

The following table summarizes sales by day of the week at a convenience store operated by a major domestic gasoline retailer. The data cover about one year, with 52 values for each day of the week.

(a) Which consecutive two-day period produces the highest total level of sales during the year?

(b) Do the distributions of the sales data grouped by day (as summarized here) overlap, or are the seven groups relatively distinct?

(c) These data summarize sales over
 consecutive days. With that in mind, what important aspect of these data is hidden by this table?