The average total cost for printing $10,000$ copies of an issue of a magazine is $$0\mathrm{.}45$

per copy. For $20,000$ copies, the average total cost is $$0\mathrm{.}35$ apiece; for $30,000,$ the

average total cost is $$0\mathrm{.}30$ per copy. The average total cost continues to decline

slightly over every level of output that the publishers of the magazine have

considered. Sketch the approximate shapes of the average and marginal cost curves.

What are some variable costs of publishing magazines? Some fixed costs?