Question

the students of three classes a b and c take a test. the average marks of classes a and b put together is 71. the average marks of classes b and c put together is 76. the average marks of class a and c put together is 79. find the range of the average marks (p) of all the three classes put together.

Answer 1

A+B=71
B+C=76
C+A=79
2(A+B+C)=216
SO,A+B+C = 216/2 i.e. 108

Answer 2

Given,

Average marks of a and b =71, average marks of b and c =76, and average marks of a and c = 79.

To Find,

The

Solution,

The formula for calculating the average is

Average = sum of observations/number of observations

So,

(a+b)/2 = 71

a+b = 142------------(1)

(b+c)/2 = 76

b+c = 152-----------(2)

(a+c)/2 = 79

a+c = 158------------(3)

Now adding the 1st, 2nd, and 3rd equation

2(a+b+c) = 452

a+b+c = 226

Now,

(a+b+c)/3 = 226/3 = 75.3

Hence, the range of all three numbers put together is 75.3