($$\sigma$$ unknown) $$t_{c}=\frac{\overline{X}-\mu_{0}}{s / \sqrt{n}}$$
($$\sigma$$ known) $$Z_{c}=\frac{\overline{X}-\mu_{0}}{\sigma / \sqrt{n}}$$
Table $$\PageIndex{6}$$ Test Statistics for Test of Means, Varying Sample Size, Population Known or Unknown