In long-run equilibrium, all firms in the industry earn zero economic profit. why is this true? all firms in perfectly competitive industries earn zero economic profit in the long run because a. firms are price takers, maximizing profit by producing where total revenue equals total cost. b. if profit were positive, then firms would produce more, increasing price, and if profit were negative, then firms would produce less, decreasing price. c. firms are price takers, maximizing profit by producing where price equals marginal cost. d. if profit were positive, then firms would enter, decreasing price, and if profit were negative, then firms would exit, increasing price. e. barriers to entry and exit prevent firms from earning positive or negative economic profit.

Rate of return, standard deviation, coefficient of variation personal finance problem mike is searching for a stock to include in his current stock portfolio. he is interested in hi-tech inc.; he has been impressed with the company's computer products and believes hi-tech is an innovative market player. however, mike realizes that any time you consider a technology stock, risk is a major concern. the rule he follows is to include only securities with a coefficient of variation of returns below 1.07. mike has obtained the following price information for the period 2015 through 2018:hi-tech stock, being growth-oriented, did not pay any dividends during these 4 years. a. calculate the rate of return for each year, 2015 through 2018, for hi-tech stock. b. assume that each year's return is equally probable and calculate the average return over this time period. c. calculate the standard deviation of returns over the past 4 years. (hint: treat this data as a sample.) d. based on b and c determine the coefficient of variation of returns for the security. e. given the calculation in d what should be mike's decision regarding the inclusion of hi-tech stock in his portfolio?