A random sample of 24 items is drawn from a population whose standard deviation is unknown. The sample mean is = 870 and the sample standard deviation is s = 25. Use Appendix D to find the values of Student's t.
(a) Construct an interval estimate of μ with 98% confidence. (Round your answers to 3 decimal places.)
The 98% confidence interval is from to
(b) Construct an interval estimate of μ with 98% confidence, assuming that s = 50. (Round your answers to 3 decimal places.)
The 98% confidence interval is from to
(c) Construct an interval estimate of μ with 98% confidence, assuming that s = 100. (Round your answers to 3 decimal places.)
The 98% confidence interval is from to
(d) Describe how the confidence interval changes as s increases.
The interval stays the same as s increases.
The interval gets wider as s increases.
The interval gets narrower as s increases.