Chapter 8, Problem 134LM

a.

To determine

Find the 90% confidence interval for the population mean.

b.

To determine

Test the null hypotheses $H_0:\mu =80$ against the alternative $H_{\text{a}}:\mu <80$ at the level of significance $\alpha =0.05$.

c.

To determine

Test the null hypotheses $H_0:\mu =80$ against the alternative $H_{\text{a}}:\mu \ne 80$ at the level of significance $\alpha =0.01$.

d.

To determine

Find the 99% confidence interval for the population mean.

e.

To determine

Obtain the sample size required to estimate the true population mean within 1 unit with 95% confidence interval.