=+14. Sometimes, rather than wishing to determine the mean value of x, an investigator wishes to determine the mean value of some function of x. Suppose, for example, that a repairman assesses a fixed charge of

$25 plus $40 an hour that he spends on a job. Then the revenue resulting from a job that takes x hours is h(x) 5 25 1 40x. If x is a continuous variable, the mean value of any function h(x) is computed similarly to the way in which  itself is computed:

h(x)5 1h(x) f(x) dx.