8.4 Choosing Output in the Short Run MC Price (dollars per unit)） 50 Lost profit for Lost profit for 92>q D 91<9 40 AR=MR=P ATC AVC 30 20 10 2 3 5 10 11 90 Output A Competitive Firm Making a Positive Profit8.4 Choosing Output in the Short Run A Competitive Firm Making a Positive Profit