How do I figure out number 4? Do I need to draw a graph for this?

4. The following schedule summarizes the sales situation confronting an oligopolist. Identify the profit-maximizing rate of output in a situation where marginal cost (per unit) is constant at $11. Price per unit $8 $10 $12 $14 $16 $17 $18 $19 $20 Quantity Demanded 10 9 8 7 6 5 4 3 2 5 How