A random sample of 10 items gives x- = 614.5 and s = 42.9. (a) Use a

Question:

A random sample of 10 items gives x- = 614.5 and s = 42.9.
(a) Use a hypothesis test to determine whether there is sufficient evidence for the experimenter to conclude that the population average is not 600.
(b) Construct a 99% two-sided confidence interval for the population average.
(c) If a 99% two-sided confidence interval for the population average is required with a total length no larger than 30. approximately how many additional items do you think need to be sampled?