The Chief Technology Officer (CTO) of a company, Ann, is putting together a hardware budget for the next 10 years. She is asking for the average lifespan of each hardware device so that she is able to

Annualized Loss Expectancy (ALE) is a financial calculation used in risk management to quantify the expected monetary loss due to a risk event over a year, not the physical lifespan of hardware.

Mean Time To Repair (MTTR) measures the average time required to repair a failed system or component and return it to operational status, which relates to recovery, not total operational lifespan.

Mean Time Between Failures (MTBF) measures the average time between failures for *repairable* systems, implying repair and continued use, whereas MTTF directly addresses the expected total operational life before a non-repairable item needs replacement.

Mean Time To Failure (MTTF) represents the average time a non-repairable component or system is expected to operate before it fails. Ann needs to estimate the total operational lifespan of hardware for replacement budgeting, making MTTF the most suitable metric for determining when devices will need to be replaced.