H19-338_V3.0 · Question #146
If the MTTR (the mean time to repair) Is fixed, the larger MTBF (the mean time between failures), the higher the system availability.
The correct answer is A. TRUE. Option A is correct because system availability is calculated as MTBF / (MTBF + MTTR). When MTTR is held constant, increasing MTBF makes the numerator grow faster than the denominator, driving the ratio closer to 1 (or 100%). For example, with MTTR fixed at 1 hour: an MTBF of 9…
Question
If the MTTR (the mean time to repair) Is fixed, the larger MTBF (the mean time between failures), the higher the system availability.
Options
- ATRUE
- BFALSE
How the community answered
(27 responses)- A81% (22)
- B19% (5)
Explanation
Option A is correct because system availability is calculated as MTBF / (MTBF + MTTR). When MTTR is held constant, increasing MTBF makes the numerator grow faster than the denominator, driving the ratio closer to 1 (or 100%). For example, with MTTR fixed at 1 hour: an MTBF of 9 hours gives 90% availability, while an MTBF of 99 hours gives 99% availability.
Option B is wrong because it contradicts the math - a longer average time between failures means the system spends more time running and less time being repaired relative to its total operational cycle.
Memory tip: Think of MTBF as "time working" and MTTR as "time broken." The formula is Availability = Working / (Working + Broken). Fix the broken time, increase the working time, and availability must go up.
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