Suppose there are three consumers of a public good with the following marginal benefits of consumption related to the quantity of the public good provided:

Consumer 1: MB₁ = 5 2Q

Consumer 2: MB₂ = 4 Q

Consumer 3: MB₃ = 3 Q

Calculate and draw the total marginal benefit function of the public good in a fully labelled diagram. If the marginal cost of producing the public good is MC = 2Q, what is the efficient quantity and how much should each consumer contribute to its provision if it were to provided at the efficient level (assuming the non-rival and non-excludable problems could be resolved)?