Question

One solution is 10% acid and another is 4% acid how many cubic cm of each should be mixed to obtain 150 cubic cm of a solution that is 6% acid?

Answer 1

Let x cubic cm of 10% acid is mixed with (150-x) cubic cm of 4% solution to obtain 150 cubic cm that is 6% acid .

Therefore the equation is

$0.1x + 0.04(150-x) = 0.06*150 \\ 0.1x + 6 -0.04x = 9$

Combining like terms, we will get

$0.06x = 3$

Dividing both sides by 0.06,

$x =  \frac{3}{0.06} \\ x = 50 \ cubic \ cm$

50 cubic cm of 10% acid is mixed with

$(150-50)=100 \ cubic \ cm$

of 4% solution to obtain 150 cubic cm that is 6% acid .