document.write( "Question 530658: a student earned scors of 83, 78, and 77 on three of four tests. what must the student score on the fourth test to have an average (arithmetic mean) of exactly 80?
\n" ); document.write( "80
\n" ); document.write( "82
\n" ); document.write( "84
\n" ); document.write( "85
\n" ); document.write( "86 \n" ); document.write( "

Algebra.Com's Answer #350184 by Earlsdon(6294) $\"\"$ $\"About$

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Let the score on the fourth test be x, then...
\n" ); document.write( " $\"%2883%2B78%2B77%2Bx%29%2F4+=+80\"$ Simplify.
\n" ); document.write( " $\"%28238%2Bx%29%2F4+=+80\"$ Multiply both sides by 4.
\n" ); document.write( " $\"238%2Bx+=+320\"$ Subtract 238 from both sides.
\n" ); document.write( " $\"x+=+82\"$
\n" ); document.write( "The student must earn a score of 82 on the fourth test to achieve an overall average of 80. \n" ); document.write( "

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