Answer:
24 ounces
Explanation:
Here's a more intuitive approach to use here.
You know that your initial solution has a percent concentration, presumably volume by volume, of
25
%
. This means that any volume of this solution contains
1
part solute and
3
parts solvent.
The target solution must have a concentration of
10
%
, which means that any volume of this solution will contain
1
part of solute and
9
parts solvent.
Your starting solution has a volume of
16
ounces, or
4
parts, each with a volume of
4
ounces.
In order to get to a solution that has a total of
10
parts, you must add
6
parts of solvent to the initial solution. Since we know that
1 part
=
4 ounces
it follows that you must add
6
parts
⋅
4 ounces
1
part solvent
=
24 ounces
of distilled water, which is your solvent, to the initial solution.
The target solution will contain
1
part solute and
9
parts distilled water for a total of
10
parts of solution, and hence have a percent concentration of
10
%
.