Mean value - Statistical Aspects of Variability

The arithmetical mean value (µ, mu) of the measurements can be readily calculated, as follows. Let the class mid- point values be denoted as x₁, x₂, x₃, etc, and the frequency in each class as f₁, f₂, f₃, etc. Let N be the total number of measurements (200 in this case). Select a convenient value (V) close to the expected mean value, say 505 in this case. Calculate the arithmetical mean value (µ) as:

µ = (f₁ (x₁-V) +f₂(x₂-V) + f₃ (x₃-V)... /N) + V

In this case

µ= (1(-15) +10(-10) +52(-5) + 63(0) + 56(5) + 16(10) +2(15)/200) + 505

= 505.48mg