One sample t-test, for testing population mean to a specified value $(\mu_0)$ is given by :

$t=\frac{\overline{x}-\mu_0}{S/n}$ $t=\frac{\overline{x}-\mu_0}{S/\sqrt{n}}$ $t=\frac{\overline{x}-\mu_0}{S/n^2}$ $t=\frac{\overline{x}-\mu_0}{\sqrt{S}/n}$

$t=\frac{\overline{x}-\mu_0}{S/\sqrt{n}}$