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Railways PYQCBT 1 2016

RRB NTPC · Question 80

B is thrice as efficient as A and C is 0.75 times as efficient as A. What is the ratio of number of days taken by A, B and C when they work individually?

  1. 4 : 1 : 3

  2. 3 : 1 : 4

  3. 2 : 3 : 1

  4. 5 : 1 : 2

Show answer & explanation

Answer: (B) 3 : 1 : 4

Explanation

Take A's efficiency as 1, so B = 3 and C = 0.75. Days taken are inversely proportional to efficiency: 1 : 1/3 : 4/3. Multiplying by 3 gives 3 : 1 : 4.