Five simple formulas for all parametric statistics

List of the five simple formulas that you need for parametric Statistics.

These are the five formula that you need in order to analyze your data at college as well as graduate school and post doc work. $$Mean \; formula \quad \bar{X} ={\sum{X} \over {n}}$$
$$Variance \; formula \quad s^2 ={\sum{({X}-{\bar{X})}}^2 \over {n-1}}$$
$$ F \; ratio \; formula \quad F={{MS_{between}} \over {MS_{within}}}$$
$$ Paired \; t-test \; formula \quad {t_{paired}}= {\bar{X}_D \over \sqrt {s^2 \over {n}}}$$
$$t-test \; formula \quad t= {{\bar{X_1}-{\bar{X_2}}} \over \sqrt{{s_1}^2 \over {n_1}}+\sqrt{{s_2}^2 \over {n_2}}}$$