The Human Factors and Systems (HFS) department is trying to determine which of two Printers to purchase. Both machines will satisfy the department's needs. Machine 1 costs $1500 and has a warranty contract, which, for an annual fee of $120, covers all the repairs. Machine 2 costs $2000, and its annual maintenance cost is a random variable. At present time, the HFS department believes there is a 30% chance that the annual maintenance cost for machine 2 will be $50, a 30% chance it will be $100 and a 40% chance it will be $150. Before the purchase decision is made, the department can have a certified technician to evaluate the quality of machine 2. If the repairer believes that machine 2 is satisfactory, there is a 70% chance that its annual maintenance cost will be $50, and a 30% chance it will be $100; if the repairer believes that machine 2 is unsatisfactory, there is a 20% chance that the annual maintenance cost will be $50, a 50% chance it will be $100 and a 30% chance it will be $150. Currently it is expected that there is a 50% chance that the technician will give a satisfactory report, and the repairer will charge $50, what should HFS department do? Construct a decision tree to help HFS find the solution.
