- The concept of the median of a set of data can also be applied
to the probability distribution of a random variable. If x is a
random variable with density function f (x), then the median of
this distribution is defined to be the value for which
half the area under the density curve lies to the left of . That
is,
is the solution to the equation .
- Suppose the lifetime x of an electronic assembly follows an
exponential distribution with an
MTBF of 1000 hours (see Example 5.12
for the definition of MTBF). Find the median of this distribution.
The median is the time by which half of all such assemblies will
break down.
- Is the median time to failure from part (a) larger or smaller
than the mean time before failure
(MTBF)?
- From your answer to part (a), find a general formula (for any
value of MTBF) for expressing
the median time to failure in terms of
the mean time before failure.