Question

A random sample of 12 items is drawn from a population whose standard deviation is unknown. The sample mean is x¯ = 800 and the sample standard deviation is s = 10. Use Appendix D to find the values of Student’s t. (a) Construct an interval estimate of μ with 95% confidence. (Round your answers to 3 decimal places.) The 95% confidence interval is from 793.650 793.650 Correct ✓ to 806.351 806.351 Correct ✓ (b) Construct an interval estimate of μ with 95% confidence, assuming that s = 20. (Round your answers to 3 decimal places.) The 95% confidence interval is from 787.299 787.299 Correct ✓ to 812.702 812.702 Correct ✓ (c) Construct an interval estimate of μ with 95% confidence, assuming that s = 40. (Round your answers to 3 decimal places.) The 95% confidence interval is from 774.596 774.596 Incorrect x to 825.403 825.403 Incorrect x (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.

Answer 1