Overhead costs are not fixed (see last 10 yrs in Exhibit 3)
SGA/Sales: 17.9% (1958) to 27.2% (1967)
Reasonable to include an increase from years 5 to 10
How much?
Costs increase by $54,000/year for 10 years
Total of $540,000
Yearly cost from years 5-10 = $540,000/6
$90,000
Graduated scale?