Question

"paul and paula are the only members of society. the table above gives their marginal benefits from missile gunboats, a public good. determine the marginal benefit to society of the second missile gunboat."

Answer 1

The marginal benefir on the second boat will definitely increase.
The marginal benefit will tend to rise until it hit a certain amount where any addition to the same product will just seem abundant.
The point where the marginal benefit started to fall almost never exist on the secon purchase.