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 x_{1}, x_{2}, x_{3}, etc, and the frequency in each class as f_{1}, f_{2}, f_{3}, 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 = (f_{1} (x_{1}-V) +f_{2}(x_{2}-V) + f_{3} (x_{3}-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