City Guilds Model Questions Vol1 2020 Engineering Question 32
Practice objective / multiple choice question 32 from the 2020 City Guilds Model Questions Vol1 Engineering examination.
A machine component fails according to an exponential distribution with constant failure rate \(\lambda = 2\times10^{-4}\ \text{h}^{-1}\). Corrective maintenance after a failure costs \(C_c = 8{,}000\) N and incurs a downtime of 5 h. Preventive maintenance performed at a fixed interval \(T\) costs \(C_p = 1{,}500\) N and requires 2 h downtime. Assuming the age‑replacement policy, the expected cost per operating hour for a given \(T\) is\n\[\nE(T)=\frac{C_p + C_c\bigl(1-e^{-\lambda T}\bigr)}{T + 2 + 5\bigl(1-e^{-\lambda T}\bigr)}\n\]\nCalculate \(E(T)\) for \(T = 2{,}000\) h and \(T = 3{,}500\) h, and state which interval gives the lower expected cost per hour.
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About This Question
This is City Guilds Model Questions Vol1 2020 Engineering Question 32. It is one of the objective questions from the 2020 City Guilds Model Questions Vol1 Engineering examination.
Difficulty level: Hard .
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