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

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

Step-by-step 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.