Question 783376
Let {{{ x }}} = liters of 1% solution needed
{{{ .01x }}} = liters of chemical in 1% solution
{{{ .04*12 = .48 }}} liter of chemical in 4% solution
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{{{ ( .01x + .48 ) / ( x + 12 ) = .02 }}}
{{{ .01x + .48 = .02*( x + 12 ) }}}
{{{ .01x + .48 = .02x + .24 }}}
{{{ .01x = .24 }}}
{{{ x = 24 }}}
24 liters of 1% solution are needed
check:
{{{ ( .01x + .48 ) / ( x + 12 ) = .02 }}}
{{{ ( .01*24 + .48 ) / ( 24 + 12 ) = .02 }}}
{{{ ( .24 + .48 ) / 36 = .02 }}}
{{{ .72 = .02*36 }}}
{{{ .72 = .72 }}}
OK