Question 771356
Let {{{ w }}} = liters of water to be added
{{{ .49*3 = 1.47 }}} liters of boric acid in 49% mixture
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{{{ 1.47 / ( w + 3 ) = .42 }}}
{{{ 1.47 = .42*( w + 3 ) }}}
{{{ 1.47 = .42w + 1.26 }}}
{{{ .42w = .21 }}}
{{{ w = .5 }}}
.5 liters of water must be added
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Check:
{{{ 1.47 / ( .5 + 3 ) = .42 }}}
{{{ 1.47 = .42*3.5 }}}
{{{ 1.47 = 1.47 }}}
OK