How much water must be added to 20 ounces of a 15% solution of argyrol to reduce it to a solution that is 10% argyrol

Question

What is the answer to the problem

Answer 1

Remember that water is a 0% solution of argyrol (since there's no argyrol in it). Let's write an equation where x = ounces of water.



The amount of argyrol in a given solution is (percent)(amount). So:

There are 0.0x = 0 ounces of argyrol in the water solution.

There are 0.15(20) = 3 ounces of argyrol in the 15% solution.

There are 0.1(20 + x) = 0 + 3 ounces of argyrol in the resulting 10% solution.



Use that last equation and solve for x:

0.1(20 + x) = 3
2 + 0.1x = 3
0.1x = 1
x = 10 ounces of water