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17 Feb 2022, 02:07
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Hi Guys,
The question is:
A certain quantity of 40% concentration solution is replaced with 25% concentration solution such that the
concentration of the combined amount is 35%. What’s the ratio of the amount of solution that was replaced to
the amount of solution that was not replaced?
A) 1:3
B) 1:2
C) 2:3
D) 2:1
E) 3:1
My answer is 2:1, but then the answer is different. Why am I failing at this?
Here's what I did:
Let A = 40% solution
Let B 25% solution
Let T = 35% solution (T = new solution)
I assume four things:
T's total solution = 100ml (easy math)
A's total solution = 100 - x
B's total solution = x
A + B = T
A: 0.4(100-x) = 40 - 0.4x
B: 0.25x
T: 0.35*100 = 35
Therefore:
1) 40 - 0.4x + 0.25x = 35
2) x = 3.33
So if B = 33.33, A has to be 100-33.33 = 66.66.
Ratio of A (replaced solution) to B (added solution) = A:B = 66.66:33.33 = 2:1.
My answer is D!
But it's wrong. Why?
The question is:
A certain quantity of 40% concentration solution is replaced with 25% concentration solution such that the
concentration of the combined amount is 35%. What’s the ratio of the amount of solution that was replaced to
the amount of solution that was not replaced?
A) 1:3
B) 1:2
C) 2:3
D) 2:1
E) 3:1
My answer is 2:1, but then the answer is different. Why am I failing at this?
Here's what I did:
Let A = 40% solution
Let B 25% solution
Let T = 35% solution (T = new solution)
I assume four things:
T's total solution = 100ml (easy math)
A's total solution = 100 - x
B's total solution = x
A + B = T
A: 0.4(100-x) = 40 - 0.4x
B: 0.25x
T: 0.35*100 = 35
Therefore:
1) 40 - 0.4x + 0.25x = 35
2) x = 3.33
So if B = 33.33, A has to be 100-33.33 = 66.66.
Ratio of A (replaced solution) to B (added solution) = A:B = 66.66:33.33 = 2:1.
My answer is D!
But it's wrong. Why?
Archived Topic
Hi there,
This topic has been closed and archived due to inactivity or violation of community quality standards. No more replies are possible here.
Where to now? Join ongoing discussions on thousands of quality questions in our Problem Solving (PS) Forum
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17 Feb 2022, 02:11
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piyushdabomb
Hi,
This question is discussed in detail here: a-certain-quantity-of-40-concentration-solution-is-replaced-191944.html If any questions please post there. Hope it helps.
Also, please read carefully and follow our posting rules: rules-for-posting-please-read-this-before-posting-133935.html Thank you.
THIS TOPIC IS LOCKED AND ARCHIVED.
Archived Topic
Hi there,
This topic has been closed and archived due to inactivity or violation of community quality standards. No more replies are possible here.
Where to now? Join ongoing discussions on thousands of quality questions in our Problem Solving (PS) Forum
Still interested in this question? Check out the "Best Topics" block above for a better discussion on this exact question, as well as several more related questions.
Thank you for understanding, and happy exploring!
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