document.write( "Question 1156483: In a zoo, the ratio of adults to children is 3 to 9. If there are 96 people in the zoo, how many children are there?\r
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Algebra.Com's Answer #779197 by ikleyn(52786) $\"\"$ $\"About$

You can put this solution on YOUR website!
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document.write( "The condition means that you can group all the people in groups in a way that each group contains 3 adults and 9 children.  \r\n" );
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document.write( "Each such a group contains 3+9 = 12 persons.\r\n" );
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document.write( "Therefore, the number of such groups is   = 8.\r\n" );
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document.write( "From it, you easily conclude that the number of children is  9*8 = 72.    ANSWER\r\n" );
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document.write( "Let x be the number of children.\r\n" );
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document.write( "Then the number of adults is 96-x.\r\n" );
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document.write( "Then you write this proportion, based on the condition\r\n" );
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document.write( "     =  =  = .\r\n" );
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document.write( "Again\r\n" );
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document.write( "     = .\r\n" );
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document.write( "From this proportion,\r\n" );
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document.write( "    3*(96-x) = x.\r\n" );
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document.write( "Simplify and solve for x\r\n" );
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document.write( "    3*96 - 3x = x\r\n" );
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document.write( "    3*96 = x + 3x = 4x\r\n" );
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document.write( "    x =  = 3*24 = 72.     ANSWER  (the same as above)\r\n" );
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\n" ); document.write( "\n" ); document.write( "3. ALGEBRA solution for more advanced students (6-th grade and higher, until 90 years old)\r
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document.write( "Notice that the ratio 3:9 is the same as 1:3.\r\n" );
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document.write( "Let x be the number of adults.\r\n" );
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document.write( "Then the number of children is 3x, according to the condition.\r\n" );
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document.write( "From the condition, you have\r\n" );
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document.write( "   x + 3x = 96,\r\n" );
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document.write( "   4x = 96,\r\n" );
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document.write( "    x = 96/4 = 24.\r\n" );
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document.write( "Hence, the number of children is 3*24 = 72.\r\n" );
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