A standard quality control check on automobile batteries involves simply measuring their weight. One particular shipment from the manufacturer consisted of batteries produced in two different months, with the same number of batteries from each month. The investigator decides to stratify on months in the sampling inspection in order to observe month-to-month variation. Simple random samples of battery weights for the two months yields the following measurements (in pounds): Month A Month B
61.5 64.5
63.5 63.8
63.5 63.5
64.0 66.5
63.8 63.5
64.5 64.0
Estimate the average weight of the batteries in the population (shipment), and place a bound on the error of estimation. Ignore the fpc. The manufacturing standard for this type of battery is 65 pounds. Do you think this shipment meets the standard on the average?