SOLUTION: To make a 6% acid solution, a chemist mixes some 4% acid solution with 12 L of 10% acid solution. How much of the 4% solution must be added to the 10% solution to make the 6% acid

Question 1136765: To make a 6% acid solution, a chemist mixes some 4% acid solution with 12 L of 10% acid solution. How much of the 4% solution must be added to the 10% solution to make the 6% acid solution?

I'm guessing that I need to make x=4% but I'm not sure what I need to use for the other variable.
Found 2 solutions by rothauserc, greenestamps:
Answer by rothauserc(4718) (Show Source): You can put this solution on YOUR website!
Let x be the amount of the 4% solution needed to mix with the 10% solution to get a 6% solution
:
There are three relations to consider, the third relation is the mixture
:
1) 12 * 0.10 = 1.20 L of acid
:
2) x * 0.04 = 0.04x L of acid
:
3) (x+12) * 0.06 = 0.06(x+12)
:
1.20 +0.04x = 0.06(x+12)
:
1.20 +0.04x = 0.06x +0.72
:
0.02x = 0.48
:
x = 24
:
***************************************************************
The chemist needs 24 L of the 4% solution to make a 6% solution
***************************************************************
:
Answer by greenestamps(13200) (Show Source): You can put this solution on YOUR website!

Here is an alternative to the traditional algebraic solution method shown by the other tutor. If you understand how to use it, it will get you to the answer to any of this kind of mixture problem much faster and with far less effort.

(1) 6% is "twice as close" to 4% as it is to 10%. (6-4=2; 10-6=4)

(2) Therefore, the amount of 4% solution in the mixture must be twice as much as the amount of 10% solution.

(3) Since there are 12L of the 10% solution, you need 24L of the 4% solution.
RELATED QUESTIONS
To make a 6% acid solution, a chemist mixes some 4% acid solution with 12 L of 10% acid... (answered by josgarithmetic,greenestamps)
A chemist mixed pure acid with water to make 10 L of a 30% acid solution. How much pure... (answered by Alan3354)
A chemist mixed pure acid with water to make 10 L of a 80% acid solution. How much pure... (answered by ewatrrr)
A chemist mixed pure acid with water to make 10 L of a 40% acid solution. How much pure... (answered by colliefan)
A chemist mixed pure acid with water to make 10 L of a 80% acid solution. How much pure... (answered by josgarithmetic)
A chemist mixes an 11% acid solution with a 4 % acid solution . How many milliters of... (answered by lwsshak3)
a chemist mixes 8 l of 40% acid solution with some unknown quantity of 70% solution to... (answered by lwsshak3)
a chemist mixes a 20% acid solution with a 60%acid solution to make 40 gallons of a... (answered by mananth)
Jackie mixes some 35% acid solution with some 70% acid solution to make 100mL of a 42%... (answered by Maths68)