When calculating the standard deviation, what must be done in order to obtain an unbiased estimate of the population? add 1 to n subtract 1 from x subtract 1 from n subtract 1 from n?

What is the area of triangle abc if a = 8, b = 11, and c = 15?

1) you deposit $2,500 in an account that earns 4% simple interest. how much do you earn in eight years?

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.