InterviewSolution
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1). 1 hr. 3 min.2). 1 hr. 18 min.3). 1 hr. 24 min.4). 1 hr. 42 min. |
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Answer» Part filled by PIPES A & B in 1 hr = 1/4 Part emptied by pipe C in 1 hr = 1/10 Part emptied by pipe D in 1 hr = 1/12 Now, pipe A & B were open for = 3 hours Pipe C was open for = 3 - 1 = 2 hours Let pipe D was opened after ‘X’ hours of opening of pipe C, Pipe D was open for = (2 - x) hours Hence, part filled in 3 hours = 1/2 ⇒ Part filled by A & B - Part emptied by C & D = 1/2 ⇒ 3 × (1/4) - 2 × (1/10) - (2 - x) × (1/12) = 1/2 ⇒ 3/4 - 1/5 - (2 - x)/12 = 1/2 ⇒ 45 - 12 - 10 + 5x = 30 ⇒ 5x = 7 ⇒ x = 7/5 = 1.4 HRS = 1 hr. 24 min. ∴ Pipe D was opened after 1 hr. 24 min. of opening of pipe C |
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