Question
Two pipes A and B can fill a cistern in 27 (1/2)Â
minutes and 35 minutes respectively. Both pipes are opened. The cistern will be filled in just 25 minutes, if the pipe B is turned off after:Solution
Let the pipe B be turned off after x minutes Then, Part filled by (A + B) in x  minutes + Part filled by A in (25 - x) minutes = 1 x(2/55 - 1/35) + (25 - x) x 2/55 = 1 x/35 = 1 - 50/55  x = 35/11  or 3(2/11) minutesÂ
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