Location is known to affect the number, of a particular item, sold by an automobile dealer. two different locations, a and b, are selected on an experimental basis. location a was observed for 9 days and location b was observed for 13 days. the number of the particular items sold per day was recorded for each location. on average, location a sold 39 of these items with a sample standard deviation of 9 and location b sold 51 of these items with a sample standard deviation of 6. select a 95% confidence interval for the difference in the true means of items sold at location a and b.

T-comm makes a variety of products. it is organized in two divisions, north and south. the managers for each division are paid, in part, based on the financial performance of their divisions. the south division normally sells to outside customers but, on occasion, also sells to the north division. when it does, corporate policy states that the price must be cost plus 20 percent to ensure a "fair" return to the selling division. south received an order from north for 300 units. south's planned output for the year had been 1,200 units before north's order. south's capacity is 1,500 units per year. the costs for producing those 1,200 units follow