A random sample of 15 items is drawn from a population whose standard deviation is unknown. The sample mean is = 760 and the sample standard deviation is s = 20. Use Appendix D to find the values of Student's t.
(a) Construct an interval estimate of μ with 99% confidence. (Round your answers to 3 decimal places.)
The 99% confidence interval is from to
(b) Construct an interval estimate of μ with 99% confidence, assuming that s = 40. (Round your answers to 3 decimal places.)
The 99% confidence interval is from to
(c) Construct an interval estimate of μ with 99% confidence, assuming that s = 80. (Round your answers to 3 decimal places.)
The 99% confidence interval is from to