How to calculate z score value?
According to the formula for the calculations of the z score, it requires an Experimental result (x),Mean value (μ) and Standard deviation (σ).
Suppose that:
$$\text{Experimental result(x)}\;=\;120$$
$$\text{Mean value(μ)}\;=\;100$$
$$\text{Standard deviation(σ)}\;=\;10$$
Formule:
$$z\;=\;120\;-\;\frac{100;}{10}$$
$$z\;=\;\frac{120-100}{10}$$
$$z\;=\;\frac{20}{10}$$
$$z\;=\;+2$$