Production processes may be classified as make-to-stock processes or make-to-order processes. Make-to-stock processes are designed to produce a standardized product that can be sold to customers from the firm's inventory. Make-to-order processes are designed to produce products according to customer specifications

(Schroeder, Operations Management, 1993). In general, performance of make-to-order processes is measured by delivery time-the time from receipt of an order until the product is delivered to the customer. The following data set is a sample of delivery times (in days) for a particular make-to-order firm last year. The delivery times marked by an asterisk are associated with customers who subsequently placed additional orders with the firm.

The MINITAB stem-and-leaf display of these data is shown at the bottom of page 47.

a. Circle the individual leaves that are associated with customers who did not place a subsequent order.

b. Concerned that they are losing potential repeat customers because of long delivery times, the management would like to establish a guideline for the maximum tolerable delivery time. Using the stem-