How has human communication evolved over the years?  What are the main forms of communication between humans today?

There are two fishermen, Zach and Jacob. They would each benefit if lighthouses were built along the coast where they fish. The marginal cost of building a lighthouse is $100. The marginal benefit that Zach gets from each lighthouse is 90 - Q, where Q is the number of lighthouses. The marginal benefit that Jacob gets from each lighthouse is 40 - Q. 1. What is the efficient number of lighthouses? 2. What is Zach's marginal benefit of lighthouses at the efficient quantity? 3. Would Zach have been willing to pay for the last additional lighthouse at the efficient quantity? a) Yes b) No

Air pollution creates a negative externality—a cost suffered by a third party as a result of an economic transaction. A standard solution to a negative externality is a Pigouvian tax, a tax that raises the marginal private cost of pollution emissions to the level of the marginal social cost. The socially optimal quantity of pollution emissions is then determined by the intersection of the marginal private benefit, or demand, curve and the marginal social cost curve. The article notes that "putting a dollar value on the benefits of cleaner air has been difficult." Assuming this problem has been resolved, in the accompanying diagram, move the endpoints of line Smarginal social cost to show the marginal social cost curve. Then move the line labeled "Tax" to show the amount of the tax needed to limit emissions to the socially optimal level.

What are Apple external opportunities?