SOLUTION: A scientist mixes water (containing salt) with a solution that contains 20% salt. She wants to obtain 140 ounces of a mixture that is 15% salt. How many ounces of water and how man

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Question 1161481: A scientist mixes water (containing salt) with a solution that contains 20% salt. She wants to obtain 140 ounces of a mixture that is 15% salt. How many ounces of water and how many ounces of the 20% salt solution should she use?
Found 3 solutions by greenestamps, josgarithmetic, ikleyn:
Answer by greenestamps(13200) About Me  (Show Source):
You can put this solution on YOUR website!


If the "water" contains salt, then we need to know the percentage of salt in order to be able to solve the problem.

If the water is in fact water with no salt, then why on earth would you add the parenthetical "(containing salt)" to the statement of the problem?

Re-post, stating the problem correctly.

Answer by josgarithmetic(39618) About Me  (Show Source):
You can put this solution on YOUR website!
Assuming you omitted the work "no" in the description, for "(containing NO salt)", the description and question is for a simple dilutions.
Also, assuming "FLUID OUNCES" for volume; not "ounces".

x, how much water to add
140-x, amount of the 20% salt solution to add

%280.2%28140-x%29%29%2F140=0.15

140-x=0.15%2A140%2F0.2

highlight%28140-x=highlight%28105%29%29-----------------the volume of the 20% salt solution to use. This means highlight%28x=35%29 fluid ounces of JUST WATER WITHOUT SALT TO ADD.


The variables could have been assigned the other way around.

Answer by ikleyn(52788) About Me  (Show Source):
You can put this solution on YOUR website!
.

Bad scientist.