A distribution center for a chain of grocery stores has determined that the total amount of time (in hours) required to fill an order from a store and load the order onto a truck for shipping is a normally distributed random variable. A new inventory system has made the process more efficient, and the operations manager decides to estimate the population mean time required to fill an order and have it loaded onto a truck. He selects a random sample of 30 orders and computes the following 98% confidence intervalL (5.85, 6.65) hours. Which of the following statements is true considering the interval given above? a. 98% of all possible values for the population mean time are in this interval.
b. The margin of error for this interval estimate is 0.80.
c. The length of the interval could be decreased by using a 99% level of confidence.
d. The manager can be 98% confident that all possible times for filling the order and loading the truck are in this interval.
e. If another confidence interval using the same data that the manager used turns out to be [5.97, 6.53], then this interval is based on a smaller level of confidence.