The Doll Computer Company makes its own computers and delivers them directly to

customers who order them via the Internet. Doll competes primarily on price and speed

of delivery. To achieve its objective of speed, Doll makes each of its five most popular

computers and transports them to warehouses across the country. The computers are

stored in the warehouses from which it generally takes $1$ day to deliver a computer to

the customer. This strategy requires high levels of inventory that add considerably to

the cost. To lower these costs, the operations manager wants to use an inventory model.

He notes that both daily demand and lead time are random variables. He concludes that

demand during lead time is normally distributed, and he needs to know the mean to

compute the optimum inventory level. He observes $25$ lead time periods and records

the demand during each period. These data are recorded in Excel Worksheet Ques $5.$

The manager would like a $95\%$ confidence interval estimate of the mean demand during

lead time. From long experience, the manager knows that the standard deviation is $75$

computers.