Question 1176443
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In a class of 40 the average score was 70.25. 
The average scores for boys and girls were 68 and 73 respectively. 
How many boys were in the class.
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<pre>
Let x be the number of boys;

then the number of girls is  (40-x).


Total scores of boys is 68x;  total scores of girls is 73*(40-x).


Total scores of the class is 40*70.25 = 2810.


The equation of total scores is


    68x + 73*(40-x) = 2810.


From the equation


    x = {{{(2810-73*40)/(68-73)}}} = 22.


<U>ANSWER</U>.  There are  22  boys in the class.
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Solved.