The community bird-watching society makes and sells simple bird feeders to incease money for its conservation activities. Materials for each feeder cost $6, and society sells the average of 20 per week at price of $10 each. Society has been thinking of increasing price, so it performs the survey and determines that for every dollar increase, it loses two sales per week.
(a) Determine the function which models weekly profit in terms of price per feeder.
(b) What price must society charge for every feeder to maximize profits? Determine maximum weekly profit?