Virginia and Campbell had 100 kilograms of a 20% glycol solution. How much of a 40% glycol solution should be added to get a solution that is 35% glycol?

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Answer 1 · 2015-10-09T19:46:05

$33 1/3$ kgm

Suppose we need to add $color(red)(x)$ kgm of $color(red)(40%)$ glycol to the $color(blue)(100)$ kgm of $color(blue)(20%)$ glycol solution

The resulting mass would be $color(green)((100+x))$ kgm (at a concentration of $color(green)(25%)$ )

$color(blue)(20% xx 100) + color(red)(40% xx x) = color(green)(25% xx (100+x))$

$rArrcolor(white)("XX")color(blue)(20)+color(red)(2/5x) = color(green)(25+1/4x)$

$rArrcolor(white)("XX")(color(red)(2/5)-color(green)(1/4))x = color(green)(25)-color(blue)(20)$

$rArrcolor(white)("XX")3/20x= 5$

$rArrcolor(white)("XX")x=100/3 = 33 1/3$