Question

A scientist mixes water (containing no salt) with a solution that contains 30% salt. She wants to obtain 180 ounces of a mixture that is 15% salt. How many ounces of water and how many ounces of the 30% salt solution should she use?

Answer 1

Answer:

water : 90 ounces

salt solution: 90 ounces

Step-by-step explanation:

Call w the amount of water and call the solution containing 30% salt.

We want to get 180 ounces of a mixture with 15% salt.

So:

The amount of mixture will be:

$w + s = 180$

the amount of salt will be

$0w + 0.3s = 180 * 0.15$

$0.3s = 27$

$s = 90\ ounces$

Now we substitute the value of s in the first equation and solve for w

$w + 90 = 180$

$w = 90\ ounces$