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Railways PYQCBT 1 2016

RRB NTPC · Question 67

A tap can fill a tank in 50 minutes. If the tank has a leakage which alone is capable of emptying the tank in 2½ hours, the tank will now be filled in ______. A. 1 hour B. 1 hour 15 mins C. 1 hour 25 mins D. 1 hour 30 mins

  1. D

  2. B

  3. C

  4. A

Show answer & explanation

Answer: (B) B

Explanation

The tap fills 1/50 of the tank per minute and the leak (2½ h = 150 min) empties 1/150. Net = 1/50 − 1/150 = 2/150 = 1/75 per minute, so the tank fills in 75 minutes = 1 hour 15 minutes.