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Answer : 4 14 min 40 sec. Explanation : Answer: D) 14 min 40 sec. Explanation: Part filled in 4 minutes = 4(1/15 1/20) = 7/15 Remaining part = 1 - 7/15 = 8/15 Part filled by B in 1 minute = 1/20 1/20 : 8/15 :: 1 : k k = (8/15 )x 1 x 20 = 10( 2/3) min = 10 min 40 sec. The tank will be full in (4 min. 10 min. 40 sec) = 14 min 40 sec.

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