3 small pumps and a large pump are filling a tank. Each of the three small pumps works at 2/3rd the rate of the large pump. If all 4 pumps work together, they should fill the tank in what fraction of the time that would have taken the large pump alone?


A) \( \Large \frac{1}{5} \)th of the time

B) \( \Large \frac{1}{4} \)th of the time

C) \( \Large \frac{1}{3} \)rd of the time

D) \( \Large \frac{1}{6} \)th of the time

Correct Answer:
C) \( \Large \frac{1}{3} \)rd of the time

Description for Correct answer:
Rate of filling by each small pump = \( \Large \frac{2}{3} \)rd of that of large pump.

Therefore, rate of filling by 3 small pumps = \( \Large 3 \times \frac{2}{3} \) of that of large pump = twice of that of large pumps.

If all 4 pumps work together, they will fill as much water as that by 3 large pumps.

Therefore, time taken by 4 pumps = \( \Large \frac{1}{3} \) of the time taken by large pump.

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