ITPEC FE Morning October 2022 Question 57
ITPEC FE Morning October 2022 — Question 57 of 80
MTBF (Mean Time Between Failures) = total uptime ÷ number of failures.
Given:
- Planned operation: 22 hours/day × 100 days = 2200 hours
- Two failures with downtimes: 0.5 + 1.5 = 2 hours
- Actual uptime: 2200 - 2 = 2198 hours
Calculation:MTBF = 2198 / 2 = 1099 ≈ 1100 hours
Why not others:
- (a) 0.00091 — resembles a failure rate (1/MTBF), not MTBF itself
- (b) 1.0 — this is MTTR (mean time to repair): 2 hours / 2 = 1 hour
- (c) 2.0 — this is total downtime, not time between failures
Key rule: MTBF = total uptime / number of failures — don't confuse with MTTR (repair time) or total downtime.
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