Lead time= 5 weeks Standard Deviation of Demand= 85 units Desired cycle-service level= 99% ; Therefore z=2.33 Formula: Safety stock = Standard Deviation of Demand x Sqrt of Lead time x Safety Factor Solution: Step 1: Find the safety stock required for five-week protection interval Safety stock = Standard Deviation of Demand x Z x sqrt(lead time) = 85 units x 2.33 x sqrt(5) =442.85 ~ 443 units door knobs Step 2: Find the safety stock required for one-week protection interval. Safety stock = Standard Deviation of Demand x Z = 85 units x 2.33 x Sqrt (1) =198.05 ~ 198 door knobs Step 3: Find the safety stock reduction. Safety Reduction= safety stocks - revised safety stocks. = 443 door knobs - 198 door knobs = 245 door knobs