SOLUTION: If 100 students took a test, the class average was 76%. The girls averaged 70% and the boys averaged 80% how many girls participated in the test
Question 827520: If 100 students took a test, the class average was 76%. The girls averaged 70% and the boys averaged 80% how many girls participated in the test Answer by TimothyLamb(4379) (Show Source):
You can put this solution on YOUR website! ---
x = boys
y = girls
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x + y = 100
80x + 70y = 76*100
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put the system of linear equations into standard form:
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x + y = 100
80x + 70y = 7600
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copy and paste the above linear system in standard form into this matrix-method solver:
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solution:
x = boys = 60
y = girls = 40
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system matrix
1 1
80 70
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inverse of system matrix
-7 0.1
8 -0.1
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determinant of system matrix = -10
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