Two vessels contain mixtures of milk and water in the ratio of in the first vessel and in the ratio of in the second vessel. In what ratio should the contents be mixed such that the resultant mixture has milk and water in the ratio of .
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Did anyone else get 17/9? I used alligation with milk fractions and ended up with 17/9, but the answer says 26/9. I'm confused.
I got 17/9 too at first, but then I realized I might have mixed up the vessels. Check your alligation diagram.
Yeah, I think the answer is 17/9. Maybe the choices have a typo? 26/9 seems too high.
This one is tricky because the total volumes change when you mix. I used the formula for mixing ratios: (m1 - m3)/(m3 - m2) where m is milk fraction. But I'm not sure if I should use milk or water fractions. Help?
Use milk fractions. The formula should give the ratio of amounts of the two mixtures. But double-check your fractions: 4/13, 2/9, and 2/7.
I got 26/9. I used alligation with milk fractions: (2/7 - 2/9) / (4/13 - 2/7) = (4/63) / (2/91) = 26/9. So A is correct.
The answer is 26/9. I verified by assuming we take x liters of first and y liters of second. Then milk total = 4x/13 + 2y/9, water total = 9x/13 + 7y/9. Set ratio to 2/5 and solve for x/y. You get 26/9.
What it tests
Your ability to reason about weighted averages and the composition of mixtures.
Common trap
Averaging the percentages of two solutions without weighting by their volumes.