SOLUTION: A 280 ML solution is 20% salt. How much water should be added to make the solution 14% salt? This is an extra credit question but I really want the bonus points. Here's what I'v

Question 425353: A 280 ML solution is 20% salt. How much water should be added to make the solution 14% salt?
This is an extra credit question but I really want the bonus points. Here's what I've already tried:
20% of 280 is 56 ML. So then I found 14% of 280 and got 39.2 ML, so would my answer be 240.8 ML (I subtracted 39.2 from 280) of water would be needed to make the solution 14% salt, or am I completely off? Thank you sooo much! : )
Found 2 solutions by ankor@dixie-net.com, Gersid:
Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
A 280 ML solution is 20% salt.
How much water should be added to make the solution 14% salt?
:
Do it like this
Let w = amt of water required to accomplish this
:
Amt of salt does not change, only the percent salt changes
.20(280) = .14(w+280)
56 = .14w + 39.2
56 - 39.2 = .14w
16.8 = .14w
w =
w = 120 ml of water required
:
:
Check this
.20(280) = .14(120+280)
.20(280) = .14(400)
56 = 56
Answer by Gersid(33) (Show Source): You can put this solution on YOUR website!
Well, not quite!
Think about how much salt there is in the initial solution.
280(0.2) = 56 ml of salt.
You are not adding any salt to make the new solution, just water, so the amount of salt will be unchanged, only its concentration changes. So...
280(0.2) = (x+280)(0.14) x is the amount of water you will add.
56 = 0.14x + 39.2 Subtract 39.2 from both sides.
16.8 = 0.14x Divide both sides by 0.14
x = 120
So you would need to add 120 ml. of water to the 280 ml. of 20% salt solution to get 400 ml. of 14% salt solution.
Check:
280(0.2) = (280+120)(0.14)
56 = 400(0.14)
56 = 56
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