Your credit card has a balance of $5200 and an annual interest rate of 12%. You decide to pay off the balance over three years. If there are no further purchases charged to the card, you must pay $172.71
each month, and you will pay a total interest of $1017.56. Assume you decide to pay off the balance over
one year rather than three.

An automobile assembly line operation has a scheduled mean completion time, μ, of 12 minutes. the standard deviation of completion times is 1.6 minutes. it is claimed that, under new management, the mean completion time has decreased. to test this claim, a random sample of 33 completion times under new management was taken. the sample had a mean of 11.2 minutes. assume that the population is normally distributed. can we support, at the 0.05 level of significance, the claim that the mean completion time has decreased under new management? assume that the standard deviation of completion times has not changed.