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A customer has purchased a new machine, and he is not quite sure which maintenance policy should be adopted. According to the reliability data from the original equipment manufacturer (OEM), the machine's life follows the Weibull distribution with MTBF=1,500 hours and the standard deviation is 500 hours. The customer realizes that an unexpected downtime cost would be cf$2,000, and a scheduled downtime cost is only cp=$700. If block or age-based maintenance is adopted, he needs to stock spare part in advance, and the inventory holding cost is $1,000/part/week. Determine which maintenance policy is the most cost-effective: corrective maintenance, block replacement or age-based maintenance