document.write( "Question 293242: the average(arithmetic mean) of x and y is 5 and the average of x, y, and z is 8. What is the value of z?
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Algebra.Com's Answer #211710 by nerdybill(7384) $\"\"$ $\"About$

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the average(arithmetic mean) of x and y is 5 and the average of x, y, and z is 8. What is the value of z?
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\n" ); document.write( "From:\"the average(arithmetic mean) of x and y is 5\" we get:
\n" ); document.write( "(x+y)/2 = 5 (equation 1)
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\n" ); document.write( "From:\"the average of x, y, and z is 8\" we get:
\n" ); document.write( "(x+y+z)/3 = 8 (equation 2)
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\n" ); document.write( "Solve equation 1 for (x+y):
\n" ); document.write( "(x+y)/2 = 5
\n" ); document.write( "Multiplying both sides by 2:
\n" ); document.write( "(x+y) = 10
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\n" ); document.write( "Substitute the above into equation 2:
\n" ); document.write( "(x+y+z)/3 = 8
\n" ); document.write( "(10+z)/3 = 8
\n" ); document.write( "10+z = 24
\n" ); document.write( "z = 14 \n" ); document.write( "

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