Here you will learn what is combined mean formula and how to find combined mean with examples.
Let’s begin –
Combined Mean Formula
If ¯x1 and ¯x2 be the means of two groups having n1 and n2 terms respectively then the mean(combined mean) of their composite group is given by
Combined mean = n1¯x1+n2¯x2n1+n2
If there are more than two groups then, combined mean = n1¯x1+n2¯x2+n3¯x3+…..n1+n2+n3+….
Also Read : What is the Formula for Mean Median and Mode
Example : There are three sections A, B and C in class X with 25, 40 and 35 students respectively. The average marks obtained by section A, B and C are 70%, 65% and 50% respectively. Find the average marks of the entire class X.
Solution : n1 = 25 x1 = 70%
n2 = 40 x2 = 65%
n3 = 35 x3 = 505
ˉx = n1¯x1+n2¯x2+n3¯x3n1+n2+n3
= (25×70)+(40×65)+(35×50)25+40+35
= 1750+2600+1750100 = 6100100 = 61%