Lorraine computed a confidence interval for μ based on a sample of size 41. since she did not know σ, she used s in her calculations. lorraine used the normal distribution for the confidence interval instead of a student's t distribution. will her interval be longer or shorter than one obtained by using an appropriate student's t distribution? explain.
shorter. for d. f. = 40, zc is greater than tc. shorter. for d. f. = 40, zc is less than tc. longer. for d. f. = 40, zc is less than tc. longer. for d. f. = 40, zc is greater than tc.

Stephen thublin invests $1,000,000 in a 45-day certificate of deposit with 6.55% interest. what is the total interest income from the investment?

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.

What would the rule be for the reflection of y=-3