A random sample of 24 items is drawn from a population whose standard deviation is unknown. The sample mean is x¯
= 880 and the sample standard deviation is s = 5. 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 = 10. (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 = 20. (Round your answers to 3 decimal places.)

The 99% confidence interval is from
to

(d) Describe how the confidence interval changes as s increases.