Real-Life Communication -- Solution
Take the million hours and divide it by 0.094592 to arrive at a
MTBF (Mean Time Between Failure) value of 10,571,718 hours. A year has 8,760
hours. So, you need to divide 10,571,718 hours by 8,760 hours to arrive at
a figure in years.
Hence, this component should last about 1,207 years!
But
the component by itself cannot do anything useful. It must be combined into
a circuit with other components. Therefore, to answer the question about how
long the device will last, the calculations are repeated for each component.
The sum of component failures is then divided into one million hours.
In
other words, saying the component will last 1,207 years will not tell the
client what he needs to know -- how long before the audio amplifier fails.
That's because more components are involved than just that one.
The
MTBF of the circuit of Fig. 1 computes to be 1,000,000/1.744961 failures,
which yields an MTBF of 573,078 hours, or about 65 years.
So, your
client's small audio amplifier will last about 65 years. This is a figure
that is meaningful and understandable.
"The more complex a piece of
equipment is, the smaller the MTBF value is. Consequently, one must store
spare parts to repair equipment," observes Marv Neumeister.