document.write( "Question 776674: the average of 11 results is 30,that of the first five is 25 and that of the last five is 28.the value of 6th number is? \n" ); document.write( "

Algebra.Com's Answer #473683 by AnlytcPhil(1807) $\"\"$ $\"About$

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the average of 11 results is 30,that of the first five is 25 and that of the last five is 28.the value of 6th number is?
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document.write( "Let the 11 results be a,b,c,d,e,f,g,h,i,j,k\r\n" );
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document.write( "Multiply both sides by 11\r\n" );
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document.write( "a+b+c+d+e+f+g+h+i+j+k = 330\r\n" );
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\n" ); document.write( ">>...that of the first five is 25,...<<
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document.write( "Multiply both sides by 5\r\n" );
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document.write( "a+b+c+d+e = 125\r\n" );
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\n" ); document.write( ">>...and that of the last five is 28...<<
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document.write( "Multiply both sides by 11\r\n" );
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document.write( "g+h+i+j+k = 140\r\n" );
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document.write( "So we have these three equations:\r\n" );
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document.write( "a+b+c+d+e+f+g+h+i+j+k = 330\r\n" );
document.write( "a+b+c+d+e             = 125\r\n" );
document.write( "            g+h+i+j+k = 140\r\n" );
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document.write( "Subtract the 2nd equation from the 1st:\r\n" );
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document.write( "          f+g+h+i+j+k = 205\r\n" );
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document.write( "Subtract the third equation from that\r\n" );
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document.write( "          f+g+h+i+j+k = 205\r\n" );
document.write( "            g+h+i+j+k = 140\r\n" );
document.write( "          f           =  65\r\n" );
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document.write( "Answer 65.\r\n" );
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document.write( "Edwin

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