Answer:
$3 per unit
Explanation:
In short run a monopolist and competitive firm try to maximize their profit and minimize costs until the the marginal revenue equals to the marginal cost.
In this question the average variable cost is lower than the marginal cost the difference between both is the profit for the short run.
Economic profit = Cost saving
Economic profit = Marginal Cost - Average variable cost
Economic profit = $8 - $5
Economic profit = $3
