The U.S. Post Office is interested in estimating the mean weight of packages shipped using the overnight service. They plan to sample 300 packages. A pilot sample taken last year showed that the standard deviation in weight was about 0.15 pounds. If they are interested in an estimate that has 95 percent confidence, what margin of error can they expect? a. Approximately 0.017 poundsb. About 0.0003 poundsc. About 1.96