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Bunuel
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I did not quite understand the solution. I dont understand why we are doing 0.5(1-x) here.
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MegB07
I did not quite understand the solution. I dont understand why we are doing 0.5(1-x) here.

x is the fraction of the 1-liter solution that's replaced. So, (1 - x) liters stay, and since it's 50% alcohol, the remaining alcohol is 0.5(1 - x).

Check the discussion for alternative solutions.
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I like the solution - it’s helpful.
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I like the solution - it’s helpful.
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I like the solution - it’s helpful. very well explained
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I like the solution - it’s helpful.
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Original..........New
50% ................25%
.............30%...........
5..........................20

So O/N = 5/20 = 1/4
N/O = 4/1
N/Total = 4/5

Thus, fraction of original solution that was replaced is 4/5 = 80%
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I like the solution - it’s helpful.
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This is a great question that’s helpful for learning and I like the solution - it’s helpful.
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I like the solution - it’s helpful.
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I did not quite understand the solution. im not understanding why we have to assume exactly 1 liter as the initial volume. I setup this problem the exact same way with the proper algebraic equation, but for my initial volume I assumed 10 liters to make the math simple, and got very wonky answers so took too long AND didn't get the right answer.

sure I can just try to remember to use 1 liter as the initial volume as a filler, but why?
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karmachaser
I did not quite understand the solution. im not understanding why we have to assume exactly 1 liter as the initial volume. I setup this problem the exact same way with the proper algebraic equation, but for my initial volume I assumed 10 liters to make the math simple, and got very wonky answers so took too long AND didn't get the right answer.

sure I can just try to remember to use 1 liter as the initial volume as a filler, but why?
Because the question asks for a fraction, not an actual number of liters.

When you are solving for a fraction, the total volume is just a scaling factor. Whether you start with 1 liter, 10 liters, or 100 liters, everything scales proportionally and cancels out.

Using 1 liter simply removes unnecessary scaling and keeps the algebra clean.
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