Question

How do I use the empirical rule?

Answer 1

It can give you quick answers without looking up in tables.

Ususally, you standardise the normal distribution, and then look up its z-value in a table.
If you memorise just a few numbers, you can work quicker.
The numbers are `34,13.5 and 2.5` meaning:
`34%` of your values will be within one standard deviation above the mean, and `34%` will be within one STD below the mean.
`13.5%` will be between one and two STD above (and `13.5%` will be between one and two STD below)
The remaining two times `2.5%` will be outside that.

Below is a graph (from Wikipedia) that summarizes: