Pipes A and B can fill a tank in 18 hours and 27 hours, respectively. Pipe C is an outlet pipe. When all the three pipes are opened for 15 hours, then 5⁄36 part of the tank is filled. How much time (in hours) will C alone take to empty one-third of the tank?

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Pipes A and B can fill a tank in 18 hours and 27 hours, respectively. Pipe C is an outlet pipe. When all the three pipes are opened for 15…

3222Medium DSSSB TGT Computer Science 0 replies 1 views

Pipes A and B can fill a tank in 18 hours and 27 hours, respectively. Pipe C is an outlet pipe. When all the three pipes are opened for 15 hours, then ⁵⁄₃₆ part of the tank is filled. How much time (in hours) will C alone take to empty one-third of the tank?

Correct answer: A

Explanation

Pipes A and B fill 1/18 + 1/27 = 5/54 per hour. In 15 hours with C open, 5/36 is filled, so the net rate is 1/108 per hour. C’s rate = 5/54 − 1/108 = 9/108 = 1/12 per hour. To empty 1/3 of the tank, C needs (1/3) ÷ (1/12) = 4 hours.

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