However in this section there are two different scenarios we have to consider. Either $\sigma$ is known, or $\sigma$ is unknown.

$\sigma$ is unknown: We will use t-scores, which will be explored in the next section

$\sigma$ is known: $E=Z_{\frac{\alpha}{2}}*\frac{\sigma}{\sqrt{n}}$

$\mu$: the population mean (what we are interested in finding)

$\overline{x}$: The sample estimate for $\mu$