The price of jeans in a perfectly competitive market is $17.  Costs are as follows:
Quantity           0    1    2    3     4       5     6        7    8        9        10
Total Cost        10    17    26    37     50       65   82      101    122        145        170
MC                  7   9   11   13    15   17     19   21      23         25
ATC                 17  13  12.3 12.5  13   13.7   14.4 15.2     16.11     17.0
AVC                 7   8   9    10    11   12    13    14      15      16
- What is the profit maximizing rate of output for the firm? 
 
- What is the profit maximization rule? 
 
- At what price should the firm shut down? 
 
- What is the shutdown rule?