One item a computer store sells is supplied by a vendor who handles only that item. Demand

for that item recently changed, and the store manager must determine when to replenish it. The

manager wants a probability of at least 96 percent of not having a stockout during lead time. The

manager expects demand to average a dozen units a day and have a standard deviation of two units

a day. Lead time is variable, averaging four days with a standard deviation of one day. Assume

normality and that seasonality is not a factor.

a. When should the manager reorder to achieve the desired probability?

b. Why might the model not be appropriate if seasonality were present?