MTBF is used to quantify which aspect of reliability?

MTBF is used to quantify which aspect of reliability?

• A. The average time required to repair after a failure.
• B. The total downtime in a reporting period.
• C. The average uptime between failures.
• D. The rate of failures per hour.

Answer: (C)

Mean time between failures measures how long a repairable system typically operates before a failure occurs. It captures the average uptime, not the time spent repairing or the total downtime. In other words, MTBF describes the expected operating interval between failures, reflecting reliability of the system in its working state. It’s distinct from the time to repair (MTTR), which is about how long repairs take, and from total downtime or the raw failure rate (which is a rate rather than a duration). If a system tends to run for about 100 hours before failing and needs 10 hours to fix, the MTBF is the average of those uptime periods, illustrating how long you can expect it to stay up between failures.

Mean time between failures measures how long a repairable system typically operates before a failure occurs. It captures the average uptime, not the time spent repairing or the total downtime. In other words, MTBF describes the expected operating interval between failures, reflecting reliability of the system in its working state. It’s distinct from the time to repair (MTTR), which is about how long repairs take, and from total downtime or the raw failure rate (which is a rate rather than a duration). If a system tends to run for about 100 hours before failing and needs 10 hours to fix, the MTBF is the average of those uptime periods, illustrating how long you can expect it to stay up between failures.