Math, asked by sumityadav5641, 11 months ago

The average marks of a class of students are76.The average marks of boys and girls are 69and 83 respectively. If there are 100 boys in the class find the number of girls in the class.

Answers

Answered by CalMeNivi007
9

Answer:

The number of girls are 100

Steps to solve :-

Let number of girls unknown be x

Given the number of boys are 100

( Sum of marks of 100 boys + Sum of marks of x girls ) / ( 100 + x ) = 76

Sum of marks of 100 boys + Sum of marks of x girls = 76 × ( 100 + x ) = 7600 + 76 x ----- ( 1 )

Given the average of 100 boys is 69

==> Sum of marks of 100 boys / 100 = 69

Sum of marks of 100 boys = 69 × 100 = 6900

Given the average of x girls = ( Sum of marks of x girls ) / x = 83

So, Sum of marks of x girls = 83 x

In ( 1 ) ,

6900 + 83 x = 7600 + 76 x

83 x - 76 x = 7600 - 6900

7 x = 700

x = 700 / 7

x = 100

Therefore, the number of girls are also 100

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