Multiple choice

How much time a tank would take to be filled by 3 pipes which diameters are 2 cm, 3 cm and 4 cm running together, when the largest pipe alone takes 58 minutes time to fill the tank. [Note:The amount of water flowing in each pipe is proportional to the square of its diameter.]

  1. 25 minutes.

  2. 30 minutes.

  3. 27 minutes

  4. 32 minutes

  5. 28 minutes
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Flow is proportional to d^2. Flow rates: 4, 9, 16. Largest pipe (16) fills in 58 mins. Tank capacity = 16 * 58 = 928 units. Total flow rate = 4 + 9 + 16 = 29. Time = 928 / 29 = 32 minutes.

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