A random sample of 12 items is drawn from a population whose standard deviation is unknown. The sample mean x(line over the top)=800 and the sample standard deviation is s=10. Use appendix D to find the values of students t.

A. Construct an interval estimate of u with 95% confidence (round your answers to 3 decimal places)

The 95% confidence interval is from _______ to _______

B. Construct an interval estimate of U with 95% confidence assuming that s=20 (round to 3 decimal places)

The 95% confidence interval is from _______to________

C. Construct an interval estimate of U with 95% confidence assuming that s=40 (round t0 3 decimal places)

The 95% confidence interval is from ______ to________