SKILL BUILDER I
In Exercises 6.135 to 6.140, use the $t$-distribution and the sample results to complete the test of the hypotheses. Use a 5% significance level. Assume the results come from a random sample, and if the sample size is small, assume the underlying distribution is relatively normal.
6.135 Test $H_0: \mu = 15$ vs $H_a: \mu > 15$ using the sample results $\bar{x} = 17.2$, $s = 6.4$, with $n = 40$.
6.136 Test $H_0: \mu = 100$ vs $H_a: \mu < 100$ using the sample results $\bar{x} = 91.7$, $s = 12.5$, with $n = 30$.
6.137 Test $H_0: \mu = 120$ vs $H_a: \mu < 120$ using the sample results $\bar{x} = 112.3$, $s = 18.4$, with $n = 100$.
6.138 Test $H_0: \mu = 10$ vs $H_a: \mu > 10$ using the sample results $\bar{x} = 13.2$, $s = 8.7$, with $n = 12$.
6.139 Test $H_0: \mu = 4$ vs $H_a: \mu \ne 4$ using the sample results $\bar{x} = 4.8$, $s = 2.3$, with $n = 15$.
6.140 Test $H_0: \mu = 500$ vs $H_a: \mu \ne 500$ using the sample results $\bar{x} = 432$, $s = 118$, with $n = 75$.
