# Thread: percent of a solution...

1. ## percent of a solution...

ok here is the question..

how many quarts of alcohol must be added to 10 quarts of a 25% alcohol solution to produce 40% alcohol solution?

i dunno i jus feel like i have too many unknowns..

i tried to use barrels to make sense of the problem..

in the first barrel i have 10 gallons of 25% solution + X gallons of Y% which will yield (10 +X) gallons of 40% solution?

ok where did i go wrong with this problem, because its not working out.

2. ## Re: percent of a solution...

Originally Posted by slapmaxwell1
ok here is the question..

how many quarts of alcohol must be added to 10 quarts of a 25% alcohol solution to produce 40% alcohol solution?

i dunno i jus feel like i have too many unknowns..

i tried to use barrels to make sense of the problem..

in the first barrel i have 10 gallons of 25% solution + X gallons of Y% which will yield (10 +X) gallons of 40% solution?

ok where did i go wrong with this problem, because its not working out.

Let the amount of alcohol added be x quarts.

Then you have 10/4 + x = (10 + 4x)/4 quarts of pure alcohol in a volume of 10 + x quarts.

You require (10 + 4x)/[4(10 + x)] = 0.4 => x = .....

3. ## Re: percent of a solution...

Hi slapmaxwell1,
Let x = the qts of 100% alc to be added to 10 qts of 25% alc to make x+10 qts of 40% alc
equation of alc balance x*1 + 10*(.25) = (10+x)*(.4) Solve for x