Multiply the number of key classes (step 3) by the
multiplier to obtain an estimate for the number of
support classes.
Multiply the total number of classes (key + support)
by the average number of work-units per class.
Lorenz and Kidd suggest 15 to 20 person-days per
class.
Cross check the class-based estimate by multiplying
the average number of work-units per use-case