I got stumped by what should be a simple econ question but I cannot figure it out. It goes like this:

Suppose the total cost for various levels of output for a competitive firm are given in the table below:
(Quantity)(0,1,2,3,4,5,6,7,8,9)**(TotalCost)(10,12 ,15,19,24,30,37,46,55,65)

How many units should the firm produce if the market price is $8? Well i know the answer to that is 6 (i think)

But what price will this firm charge in the long run? Thoughts? Oh and how you got the answer would be nice cause i tried what i thought was correct.