document.write( "Question 292486: A student earned scores of 83, 78, and 77 on three of four test. What must the student score on the fourth test to have an average(arithmetic mean) of exactly 80? \n" ); document.write( "

Algebra.Com's Answer #211246 by nerdybill(7384) $\"\"$ $\"About$

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A student earned scores of 83, 78, and 77 on three of four test. What must the student score on the fourth test to have an average(arithmetic mean) of exactly 80?
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\n" ); document.write( "Let x = score on fourth test
\n" ); document.write( "then
\n" ); document.write( "(83+78+77+x)/4 = 80
\n" ); document.write( "(238+x)/4 = 80
\n" ); document.write( "238+x = 320
\n" ); document.write( "x = 320-238
\n" ); document.write( "x = 82
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