Question 1038405
Let {{{ x }}} = liters of 8% acid to be added
{{{ .02*8 = .16 }}} liters of acid in 2% solution
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{{{ ( .16 + .08x ) / ( 8 + x ) = .04 }}}
{{{ .16 + .08x = .04*( 8 + x ) }}}
{{{ .16 + .08x = .32 + .04x }}}
{{{ .04x = .16 }}}
{{{ x = 4 }}}
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She should add 4 liters of 8% acid
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check:
{{{ ( .16 + .08x ) / ( 8 + x ) = .04 }}}
{{{ ( .16 + .08*4 ) / ( 8 + 4 ) = .04 }}}
{{{ ( .16 + .32 ) / 12 = .04 }}}
{{{ .48 = .04*12 }}}
{{{ .48 = .48 }}}
OK