In a vessel , there are 20 litres of alcohol . An operation is defined as…
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In a vessel , there are 20 litres of alcohol . An operation is defined as taking out five litres of what is present in the vessel and adding 10 litres of pure water to it . What is the ratio of alcohol to water after two operations ?
- A.
3:2
- B.
1:6
- C.
2:3
- D.
1:5
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Correct answer: C
Ans: 2:3
Final concentration = Initial concentration (1 - replacement quantity / final volume)
After 1st process: Concentration = 1(1-10/25) = 3/5
After 2nd process: Concentration = (3/5)(1 - 10/30) = 2/5
So ratio of alcohol : water = 2:3