In: Statistics and Probability
A tire manufacturer warranties its tires to last at least 20 comma 000 miles or "you get a new set of tires." In its experience, a set of these tires last on average 28 comma 000 miles with SD 5 comma 000 miles. Assume that the wear is normally distributed. The manufacturer profits $200 on each set sold, and replacing a set costs the manufacturer $400. Complete parts a through c.
(a) What is the probability that a set of tires wears out before 20 comma 000 miles? The probability is nothing that a set of tires wears out before 20 comma 000 miles. (Round to four decimal places as needed.)
(b) What is the probability that the manufacturer turns a profit on selling a set to one customer? The probability is nothing that the manufacturer turns a profit on selling a set to one customer. (Round to four decimal places as needed.)
(c) If the manufacturer sells 500 sets of tires, what is the probability that it earns a profit after paying for any replacements? Assume that the purchases are made around the country and that the drivers experience independent amounts of wear. The probability is nothing that the manufacturer earns a profit after paying for any replacements on 500 sets of tires. (Round to four decimal places as needed.)