Consider a drilling process (normally distributed) with a target hole length of 2.60 inches. The upper specification limit is 2.80 inches, and the lower specification limit is 2.55 inches. The machine has a natural process variability of = 0.10 inches. Holes that are drilled too short cost $3.00 to fix, and holes that are drilled too long cost $10.00 to fix. If monthly production is 20,000 units, what is the expected fixing cost per month using this machine?

Z-table z-value probability z-value probability z-value probability -2.00 0.0228 -0.25 0.4013 0.50 0.6915 -1.00 0.1587 -0.20 0.4207 0.80 0.7881 -0.80 0.2119 0.20 0.5793 1.00 0.8413 -0.50 0.3085 0.25 0.5987 2.00 0.9772