Question 4 (1 point) Which costs do NOT vary with the amount of output a firm produces? O average fixed costs fixed costs and average fixed costs marginal costs and average fixed costs fixed costs Question 5 (1 point) If a firm in a perfectly competitive market doubles the number of units of output sold, what will happen to total revenue? O It will less than double. It will exactly double. It will more than double. O It will increase, but by an unpredictable amount