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CUET · MATHS · PYQ PAPER 2025

Three pipes \(A, B\) and \(C\) can fill a tank in \(12\) hours, \(15\) hours and \(20\) hours respectively. If A is open all the time and \(B\) and \(C\) are open for one hour each alternately, in how many hours will the tank be full?

  1. A \(6\) hours
  2. B \(5.5\) hours
  3. C \(8\) hours
  4. D \(7\) hours
Verified Solution

Answer & Solution

Correct Answer

(D) \(7\) hours

Step-by-step Solution

Detailed explanation

Work rate of A: \( \frac{1}{12} \) tank/hour Work rate of B: \( \frac{1}{15} \) tank/hour Work rate of C: \( \frac{1}{20} \) tank/hour Work in 1st hour (A+B): \( \frac{1}{12} + \frac{1}{15} = \frac{5+4}{60} = \frac{9}{60} \) tank Work in 2nd hour (A+C):…