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GATE 2014 EC (EC2) – Question 10

General Aptitude · Quantitative Aptitude: Arithmetic and Number Computation · 2 marks · Multiple choice

A half-full tank empties in 30 minutes at a constant drain rate. Water is pumped in while draining continues. What pumping rate fills it completely in 10 minutes?

  1. 4 times the drain rate
  2. 3 times the drain rate
  3. 2.5 times the drain rate
  4. 2 times the drain rate

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Show answer and explanation

Correct answer: (A) 4 times the drain rate

Explanation

Let the full capacity be V. The drain empties V/2 in30min, so its rate is V/60 per minute. Filling the remaining half in10min requires net inflow V/20. Therefore pumping rate=V/20+V/60=V/15, which is **4times the draining rate,A**.