how many ounces of pure salt must be added to 13oz if 30% salt solution to produce a 45% solution? pure salt is 100%. round the answer to the nearest hundredth of an oz.

Answer 1

Let s = the number of ounces of pure salt.

So, 0.13(30) = 3.9 ounces of salt in our current solution. We will add s ounces of salt, which adds both to the amount of salt and the total ounces.

s + 3.9 = 0.45(s + 13)

s + 3.9 = 0.45s + 5.85

0.55s = 1.95

s = 3.55 ounces

Let's check.

3.9 + 3.55 = 0.45(13 + 3.55)

7.45 = 0.45(16.55)

7.45 = 7.45

0 = 0

We're good.

Side note: I'm glad I did the check because I made an error and would have given you a wrong answer!

Answer 2

30% solution contains 3.9 "units" of salt

45% solution will contain 5.85 "units" of salt,

i.e. you will need to add 1.95 "units" of salt.

This assumes that the salt is a solid and that when it dissolves it does not increase the volume of the solution.