Using the data in the above table, when output increases from 4 to 9 units, the marginal cost of one of those 5 units is

Which of the following statements about private and social costs is TRUE?

A) Social costs include externalities. B) Private cost do not include externalities. C) Social costs are never smaller than private costs. D) All of the above.

The Value of Bonuses Oscar's Outdoor Signage employs salesmen to find new advertisers for existing signs. In an average month, salaried sales staff can keep 80 of 100 signs under contract in a given month. When Oscar experimented with a bonus of $100

for each sign under contract this was increased to 90 of 100 signs. How large must the contribution margin on a sign be to make it profitable to offer the bonuses?