It is claimed that automobiles are driven on average more than 20,000 kilometers per year. to test this claim, 100 randomly selected automobile owners are asked to keep a record of the kilometers they travel. would you agree with this claim if the random sample showed an average of 23,500 kilometers and a standard deviation of 3900 kilometers?

You are the manager of a large crude-oil refinery. as part of the refining process, a certain heat exchanger (operated at high temperatures and with abrasive material flowing through it) must be replaced every year. the replacement and downtime cost in the first year is $165 comma 000. this cost is expected to increase due to inflation at a rate of 7% per year for six years (i. e. until the eoy 7), at which time this particular heat exchanger will no longer be needed. if the company's cost of capital is 15% per year, how much could you afford to spend for a higher quality heat exchanger so that these annual replacement and downtime costs could be eliminated?