11.6. Autotek Limited needs a certain casting from its supplier for which the standard deviation is calculated as 150 units.

a. What safety stock should be carried to provide a service level of 90%? If the expected demand during the lead time is 1500 units, what is the order point?

b. Calculate the change in safety stock required to increase the service levels from 90% to 94%. What will be the changed order point?