Question

A scientist mixes water (containing no salt) with a solution that contains 35 % salt. She wants to obtain 245 ounces of a mixture that is 5 % salt. How many ounces of water and how many ounces of the 35 % salt solution should she use?

Answer 1

Answer. 105 ounces of water is needed.

Let W = the volume of water to be mixed in ounces).

Then the volume of the 30% salt solution needed is (210-W).

The balance equation for the salt mass is

0.3*(210-W) = 0.15*210.

Simplify and solve for W:

63 - 0.3W = 31.5,

63 - 31.5 = 0.3W,

0.3W = 31.5,

W = 31.5%2F0.3 = 105.

Answer. 105 ounces of water is needed.

Explanation: