Two inlet pipe A and B fill a tank in 2 hour and 3 hour respectiv

Two inlet pipe A and B fill a tank in 2 hour and 3 hour respectiv
| Two inlet pipe A and B fill a tank in 2 hour and 3 hour respectively. While an outlet C empty the same tank in 4 hour. If all the three pipe open together then in what time they fill the tank ? 

A. 12/7 hour

B. 13/7 hour

C. 11/7 hour

D. 10/7

Please scroll down to see the correct answer and solution guide.

Right Answer is: A

SOLUTION

Efficiency of pipe A = 1/2

Efficiency of pipe B = 1/3

Efficiency of pipe C = 1/4

Efficiency of pipe A, B and C when they open together = 1/2 + 1/3 - 1/4 = (6 + 4 - 3)/12 = 7/12

∴ Time taken by pipe A, B and C to fill the tank when they open together = 12/7 hour

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