<PRE><B>Question 149954</B>
Average(arithmetic mean) of test scores in class R: 
average score for the boys: 
Let # of boys be x; then number of points scored is 90x
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average score for the girls: 81
Let # of girls be y; then number of points scored is 81y
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average score for the class: 84
Number of boys and girls is (x+y); total # number of points scored is 84(x+y)
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Which is larger, the number of boys in the class who took the test or the number of girls in the class who took the test? 
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EQUATION:
# scored by boys + # scored by girls is 84(x+y)
90x + 81y = 84x+84y
6x  = 3y
y = 2x
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# of girls is twice the number of boys
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Cheers,
Stan H.</PRE>