There are four players each of whom has an initial endowment of $10. Each player has to decided how much of his initial endowment to invest in a public good. Each player I's payoff is given by u(i) = 0.8G + 10 - x(i), where x(i) is player I's contribution to the public good and G = x1 + x2 + x3 + x4 is the amount of the public good that is being provided.

a) What is the dominant strategy for each player?

b) what contribution levels would be efficient.