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 15% salt. How many ounces of water and how many ounces of the 35% salt solution should she use?

Answer 1

Answer:

140 ounces of water and 105 ounces of 35% salt solution.

Explanation:

Let $x$ be the ounces of water that need to be added and $y$ be the ounces of 35% solution that need to to be added.

We know that the total of ounces of water and of 35% solution must be 245 ounces:

$x+y=245$

35% of  $x$ is the salt, and since no salt is added with addition of $y$  liters of water, this must be equal to the amount of salt in the final 15% solution:

$0.35x=0.15*245$

we solve for  $x$ and get:

$x=105$

We put this value into $x+y=245$ and solve for $y$ to get:

$y=140$

Thus we have 140 ounces of water and 105 ounces of 35% solution.