document.write( "Question 313459: The oldest child in a family of four children is twice as old as the yougest. The two middle children are 13 and 15 years old. If the average age of the children is 14.5 , how old is the youngest child?
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Algebra.Com's Answer #224144 by ankor@dixie-net.com(22740) $\"\"$ $\"About$

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The oldest child in a family of four children is twice as old as the youngest.
\n" ); document.write( " The two middle children are 13 and 15 years old.
\n" ); document.write( " If the average age of the children is 14.5, how old is the youngest child?
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\n" ); document.write( "Let x = the youngest child
\n" ); document.write( "then
\n" ); document.write( "2x = the oldest child
\n" ); document.write( ":
\n" ); document.write( "\"the average age of the children is 14.5,\"
\n" ); document.write( " $\"%28x+%2B+13+%2B+15+%2B+2x%29%2F4\"$ = 14.5
\n" ); document.write( ":
\n" ); document.write( " $\"%283x+%2B+28%29%2F4\"$ = 14.5
\n" ); document.write( "Multiply both sides by 4
\n" ); document.write( "3x + 28 = 4(14.5)
\n" ); document.write( "3x + 28 = 58
\n" ); document.write( "3x = 58 - 28
\n" ); document.write( "3x = 30
\n" ); document.write( "x = $\"30%2F3\"$
\n" ); document.write( "x = 10 yrs is the youngest child
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\n" ); document.write( "Check solution (oldest child = 20)
\n" ); document.write( " $\"%2810+%2B+13+%2B+15+%2B+20%29%2F4\"$ =
\n" ); document.write( " $\"58%2F4\"$ = 14.5 \n" ); document.write( "

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