P a and P b represent the prices that citizens (a)and (b),the only two people in this nation,are willing to pay for additional units of a quantity (Q c )of the public good.Q s represents the quantity of the public good supplied by government at each of the collective prices.
-Refer to the above information.If only one unit of this public good is produced,then the marginal benefit is

Question

P a and P b represent the prices that citizens (a)and (b),the only two people in this nation,are willing to pay for additional units of a quantity (Q c )of the public good.Q s represents the quantity of the public good supplied by government at each of the collective prices. 
-Refer to the above information.If only one unit of this public good is produced,then the marginal benefit is

Quizplus · Accepted Answer

The marginal benefit for citizen (a) is $9-$3=$6 and the marginal benefit for citizen (b) is $6-$3=$3. The marginal cost is $3. Since the public good is non-rival and non-excludable, the optimal quantity is the one where marginal cost equals the sum of marginal benefits of all citizens. In this case, that is $6+$3=$9$. Therefore, producing one unit of the public good is optimal and the marginal benefit is $9-$3=$6 and the marginal cost is $3$, so the answer is D.

Pa and Pb Represent the Prices That Citizens (A)and (B),the

P_a and P_b Represent the Prices That Citizens (A)and (B),the