Page 27 - Digi Notes : Maths - 11.03.2016

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39. In three classes X, Y and Z; an algebra test is

conducted. The average score of class X is 83. The

average score of class Y is 76 and the average score of

class Z is 85. The average score of class X & Y is 79 and the

average score of class Y & Z is 81. What is the average

score of the classes X, Y and Z.?

Average Score X Average Score Y

83 76

79

 3 :  4

X Students :Y Students  3 : 4

Again ;

Average Score Y Average Score Z

76 85

81

4 : 5

Y Students : Z Students  4 : 5

Now ;

X Students :Y Students  4 : 3 

Y Students : Z Students  5 : 4   X Students :Y Students : Z Students  5 : 4 : 3


 Required Average  83 3 76 4  85 5  81 5 .
3 4  5

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