Question 475177
Let {{{a}}} = ounces of alcohol to be added
In words:
( ounces of iodine in final solution) / ( total ounces of solution) = 4%
given:
Ounces of iodine started with = {{{ .07*20 = 1.4 }}}
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{{{ 1.4 / (20 + a) = .04 }}}
{{{ 1.4 = .04*(20 + a) }}}
{{{ 1.4 = .8 + .04a }}}
{{{ .04a = .6 }}}
{{{ a = 15 }}}
15 ounces of pure alcohol must be added