3. (a) The Operation and Maintenance Manager of a company manufacturing electrical accessories prepares to formulate some well-defined elements in the technical support. List and briefly explain THREE elements in the area concerned. (5 marks) (b) The smoke detectors of the fire services system in a building are required to be maintained in good working order. The building manager believes that it could be sometimes more economical to replace the group as a whole even if some of the items are still functioning satisfactorily, than to replace each item as it fails. According to the past records of 100 smoke detectors, on an average, 80 survive for at least 1 year, 50 survive for at least 2 years, and 10 survive for at least 3 years. Furthermore, the cost of bringing the contractor to the site costs $1200 and the material cost is $300 for the replacement of one smoke detector. You are requested by the building manager to provide the following information from a survival tree. (i) The average life of detectors. (ii) (iii) The cost of individual replacement (i.e. replaced when it fails) per year. The cost of maintenance of smoke detectors at the end of three years including a complete replacement of detectors at the end of every year. (15 marks)