Calculate how much 1% salt solution must be mixed with how much 5% salt solution to make 100 milliliters of 2% salt solution. you'll need milliliters of the 5% salt solution.

Let x be the amount (the volume in milliliters) of the 5% solution to be mixed.

Then the volume of the 1% solution is 100-x milliliters.

Then your "concentration" equation is

%280.01%2A%28100-x%29+%2B+0.05%2Ax%29%2F100 = 0.02,

or, equivalently,

100-x + 5*x = 200,

which implies

4x = 100 > x = 100%2Fx = 25.

25 milliliters of the 5% solution must be mised with 100-25 = 75 milliliters of the 1% solution.

The length of what is left would be 1 1/2 feet long.

Cis your correct answer