Multiple choice

If pipe K and pipe L are inlet pipe and outlet pipe respectively. Pipe K and L both are opened simultaneously it will take twice the time than when both the pipe fill the tank. When pipe L is used for filling the tank, its efficiency remains constant. What is the ratio of efficiency of pipe K and pipe L respectively?

  1. 2:3

  2. 3:4

  3. 1:4

  4. 1:3

  5. 2:5
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Let K fill tank in k hours, L fill tank in l hours when used for filling. Time together filling: k*l/(k+l). Time with K filling, L draining: k*l/(l-k). Given: k*l/(l-k) = 2 × k*l/(k+l). Simplifying: 1/(l-k) = 2/(k+l), giving k+l = 2l-2k, so 3k = l, meaning K:L = 1:3. Option D is correct.

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