document.write( "Question 765734: For a certain student, the average of ten test scores is 80. If the high and low scores are dropped, the average is 81. What is the average of the high and low scores? \n" ); document.write( "

Algebra.Com's Answer #466452 by Edwin McCravy(20060) $\"\"$ $\"About$

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For a certain student, the average of ten test scores is 80. If the high and low scores are dropped, the average is 81. What is the average of the high and low scores?

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document.write( "Let x = the sum of highest and lowest scores\r\n" );
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document.write( "Let y = the sum of the middle 8 scores left \r\n" );
document.write( "        after the highest and lowest are dropped\r\n" );
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document.write( "Then x+y = the sum of all 10 scores

\n" ); document.write( ">>...the average of ten test scores is 80...<<

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document.write( "That says:\r\n" );
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document.write( "Multiply both sides by 10\r\n" );
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document.write( " x + y = 800

\n" ); document.write( ">>...If the high and low scores are dropped, the average is 81...<<

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document.write( "That says the average of the middle 8 scores is 81, so\r\n" );
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document.write( "Multiply both sides by 10\r\n" );
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document.write( "     y = 648\r\n" );
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document.write( "Substitute in\r\n" );
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document.write( "   x + y = 800\r\n" );
document.write( " x + 648 = 800\r\n" );
document.write( "       x = 152 = the sum of highest and lowest scores\r\n" );
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document.write( "Average of highest and lowest scores =  = 76\r\n" );
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document.write( "Edwin

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