Rate of output fixed costs average fixed costs variable costs average variable costs total cost average total cost 0 $120 -- $0 0 $120 -- 10 120 85 205 $20.50 15 120 125 245 16.33 20 120 150 270 13.50 30 120 240 360 12.00 40 120 350 470 11.75 50 120 550 670 13.40 51 120 633 753 14.76

b. at what rate of output are average fixed costs the lowest? units

c. at what rate of output are average variable costs the lowest? units

d. at what rate of output is average total cost the lowest? units