An assembly line can produce 60 units per hour. The line's hourly cost is $3600 on straight time (the first 8 hours). Workers are guranteed a minimum of 6 hours. There is a 50% premium for overtime and productivity for overtime drops by 5%. What are the average and marginal costs per unit for the following daily quantities?
a) 300
b) 400
c) 500
d) 600