The image above represents standard normal variable.
To compute for standard normal variable, three essential parameters are needed and these parameters are value (x), mean (μ) and standard deviation (σ).
The formula for calculating standard normal variable:
z = (x – μ) ⁄ σ
Where;
z = Standard Normal Variable
x = Value
μ = Mean
σ = Standard Deviation
Let’s solve an example;
Find the standard normal variable when the value is 4, the mean is 20 and the standard deviation is 26.
This implies that;
x = Value = 4
μ = Mean = 20
σ = Standard Deviation = 26
z = (x – μ) ⁄ σ
z = (4 – 20) ⁄ 26
z = (-16) ⁄ 26
z = -0.615
Therefore, the standard normal variable is -0.615.