Round answers to 3 decimal places

A random sample of 21 items is drawn from a population whose standard deviation is unknown. The sample mean is x = 910 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 / with 99% confidence. (Round your answers to 3 decimal places.) The 99% confidence interval is from to (b) Construct an interval estimate of / 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 / with 99% confidence, assuming that s = 80. (Round your answers to 3 decimal places.) The 99% confidence interval is from to