There will be no formulas.ANOVA is used when we want to compare means among three or more groups (with only two groups, you could still use ANOVA but it is easier and equivalent to use a t-test).For example, suppose you have a bunch of men and you are interested in comparing their weights ..When we divide them in a silly way, we get huge variation between and little variation within.That’s why we look at variances to compare means.ANOVA just makes all that formal and mathematical.. More details