Determining total profit at the optimal output level

Question

Question 1: Global Corp. sells its output at the market price of $9 per unit. Each plant has the costs shown below:

Units of Output	Total Cost ($)
0	9
1	11
2	15
3	21
4	29
5	39
6	51
7	65

What is the profit at each plant when operating at its optimal output level?   
   
Please specify your answer as an integer.   

Question 2: Suppose that you can sell as much of a product (in integer units) as you like at $61 per unit. Your marginal cost (MC) for producing the qth unit is given by:

MC = 9q   
       
This means that each unit costs more to produce than the previous one (e.g., the first unit costs 9*1, the second unit (by itself) costs 9*2, etc.).   
       
If fixed costs are $50, what is the optimal output level?   
       
Please specify your answer as an integer.   
            
Question 3: Assume that a competitive firm has the total cost function:   
       
TC = 1q³ - 40q² + 710q + 1700   
       
Suppose the price of the firm's output (sold in integer units) is $550 per unit.   
       
Using tables (but not calculus) to find a solution, what is the total profit at the optimal output level?   
       
Please specify your answer as an integer.