Question 196704
given:
{{{.6*500 = 300}}}ml of acid
Let {{{x}}}= ml of solution to be added
{{{.3x}}}= ml of acid added
{{{(.6*500 + .3x) / (500 + x) = .5}}}
Multiply both sides by {{{500 + x}}}
{{{300 + .3x = .5*(500 + x)}}}
{{{300 + .3x = 250 + .5x}}}
{{{.2x = 50}}}
{{{x = 250}}} ml
250 ml of a 30% solution must be added
check:
{{{(.6*500 + .3x) / (500 + x) = .5}}}
{{{(.6*500 + .3*250) / (500 + 250) = .5}}}
{{{(300 + 75) / 750 = .5}}}
{{{375 = .5*750}}}
{{{375 = 375}}}
OK