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A 24 liters cylinder containing ethylene and acetylene contains 25% ethylene by volume. A few liters of the mixture is released and replaced with equal amount of acetylene. If this process is repeated once, the cylinder is found to contain 16% ethylene by volume. How many liters of the gaseous mixture was released each time?

A) 6.2 litres
B) 5.3 litres
C) 7.2 litres
D) 4.8 litres

Correct Answer:




D) 4.8 litres

Description for Correct answer:
Let R liters be the amount of the mixture that was released each time and let M liters be the total capacity of the cylinder (which is equal to 24 liters).
\( \Large \frac{\% of\ ethylene\ left}{\% of\ ethylene\ originally\ present} = \left(1 - \frac{R}{M}\right)^{2} \)
i.e. \( \Large \frac{16\%}{25\%} = \left(1 - \frac{R}{24}\right)^{2} \)
or \( \Large \frac{\frac{16}{100}}{\frac{25}{100}} = \left(1 - \frac{R}{24}\right)^{2} \)
or \( \Large \frac{16}{25}= \left(1 - \frac{R}{24}\right)^{2} \)
or \( \Large \frac{4}{5}= \left(1 - \frac{R}{24}\right) or R\ =\ 4.8 litres \)

Part of solved Mixture and Allegation questions and answers : >> Aptitude >> Mixture and Allegation

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