Slides - Åbo Akademi

MTTF Example
A system with a constant failure rate of 0.001 failures per hour has
a MTTF of 1000 hours.
This does not mean that the system will operate correctly
for 1000 hours!
The reliability of such system at a time t is: R(t) = e −λt
Assume that t = MTTF = 1 λ
R(t) = e −1 ≈ 0.37
Any given system has only a 37% chance of functioning correctly
for an amount of time equal to the MTTF (i.e., a 63% chance of
failing in this period).