At a sales volume of 35,000 units, Thoma Corporation's sales commissions (a cost that is variable with respect to sales volume) total $448,000.
To the nearest whole dollar, what should be the total sales commissions at a sales volume of 33,200 units? (Assume that this sales volume is within the relevant range.)
a) $424,960
b) $448,000
c) $436,480
d) $472,289