City Guilds Model Questions Vol1 2017 Engineering Question 18
Practice objective / multiple choice question 18 from the 2017 City Guilds Model Questions Vol1 Engineering examination.
A machine experiences failures that follow an exponential distribution with a mean time between failures (MTBF) of 1,200 hours. Each failure requires a repair downtime of 4 hours. The plant can perform preventive maintenance at regular intervals. Each preventive maintenance action reduces the failure rate for the subsequent interval by 30\% but adds 2 hours of scheduled downtime. Assuming 100\% maintenance efficiency and neglecting other losses, what preventive‑maintenance interval (in whole hours) maximises the long‑run availability of the machine if the interval must lie between 500 and 2,500 hours?
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About This Question
This is City Guilds Model Questions Vol1 2017 Engineering Question 18. It is one of the objective questions from the 2017 City Guilds Model Questions Vol1 Engineering examination.
Difficulty level: Hard .
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