Answer
Please see the graph.
Work Step by Step
To determine the efficient quantity, the demand curve intersects the marginal cost curve. The monopolist's quantity is determined by where the marginal revenue curve intersects the marginal cost curve. (The monopolist's quantity of$Q_{M}$ is less than the efficient quantity of $Q_{E}$.)
The monopolist's price of $P_{M}$ is based on the demand curve (since we know the quantity). The shaded triangle is the deadweight loss.
The total surplus is maximized at this quantity since, at the optimal quantity, consumers would buy the efficient quantity.
