City Guilds Model Questions Vol1 2023 Engineering Question 38

Practice objective / multiple choice question 38 from the 2023 City Guilds Model Questions Vol1 Engineering examination.

City Guilds Model Questions Vol1 2023 Engineering Objective / Multiple Choice Hard Difficulty
Question 38 CITY_GUILDS_MODEL_QUESTIONS_VOL1 • 2023 • ENGINEERING • objective

A machine has a constant failure rate of \(\lambda = 0.0002\) per hour (exponential distribution). A preventive‑maintenance (PM) action restores the machine to "as‑good‑as‑new", costs \(\text{₦}500\) and requires 1 hour of downtime. An unplanned failure costs \(\text{₦}5000\) and incurs 3 hours of downtime. The monetary value of lost production is \(\text{₦}200\) per hour of downtime. If a PM is scheduled every \(T\) operating hours, determine the value of \(T\) that minimizes the expected cost per hour of operation. State the optimal policy.

Answer Options

A. Schedule preventive maintenance every 1000 operating hours; the optimal interval is 1000 h.
B. Schedule preventive maintenance every 2000 operating hours; the optimal interval is 2000 h.
Correct Answer C. Do not schedule preventive maintenance; the optimal interval is infinite (no PM).
D. Schedule preventive maintenance every 500 operating hours; the optimal interval is 500 h.
Correct Answer
C
Correct Option:
Do not schedule preventive maintenance; the optimal interval is infinite (no PM).

About This Question

This is City Guilds Model Questions Vol1 2023 Engineering Question 38. It is one of the objective questions from the 2023 City Guilds Model Questions Vol1 Engineering examination.

Difficulty level: Hard .

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