A Duopoly Example Price and Quantity Supplied The socially efficient quantity of water is 120 gallons but a monopolist would produce only 60 gallons of water So what outcome then could be expected from duopolists?A Duopoly Example: Price and Quantity Supplied • The socially efficient quantity of water is 120 gallons, but a monopolist would produce only 60 gallons of water. • So what outcome then could be expected from duopolists?