Price in a perfectly competitive industry: select one:
a. is determined by each firm, depending on its costs of production.
b. is always equal to marginal revenue for the firm.
c. must be greater than average total cost or the firm will shut down in the short run.
d. is indeterminate in the short run.

Xinhong company is considering replacing one of its manufacturing machines. the machine has a book value of $39,000 and a remaining useful life of 5 years, at which time its salvage value will be zero. it has a current market value of $49,000. variable manufacturing costs are $33,300 per year for this machine. information on two alternative replacement machines follows. alternative a alternative b cost $ 115,000 $ 117,000 variable manufacturing costs per year 22,900 10,100 1. calculate the total change in net income if alternative a and b is adopted. 2. should xinhong keep or replace its manufacturing machine