Question 149954: Average(arithmetic mean) of test scores in class R:
average score for the boys: 90
average score for the girls: 81
average score for the class: 84
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?
They say the number of girls is larger, but I have no idea how they get this. Any help would be appreciated. Thanks!
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! 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.
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