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Three pipes A, B and C together can fill a cistern in 6 hours. After working together for 2 hours, C is closed and A and B fill the remaining cistern in 8 hours. Then the time in which the cistern can be filled by pipe C alone will be: |

A) 11 hours
B) 9 hours
C) 12 hours
D) 10 hours
Correct Answer :12 hours Explanation :Three Pipes A,B and C together filled a tank in 6 hours A and B can fill remaining in 8 hours, (A + B)'s 8 hour's work = 2/3 Therefore C's 1 hour's work C alone can fill the tank in 12 hours |

Two pipes A and B can fill a cistern in 4 and 6 minutes respectively. If both the pipes kept turned on alternatively for one minute each starting from A, how long will it take to fill the cistern? |

A) 3(3/7) minutes
B) 6 minutes
C) 4(2/3) minutes
D) 6(6/7) minutes
Correct Answer :4(2/3) minutes Explanation :As the pipes are operating alternatively for one minute, thus (A+B)'s 2 minutes job is =(1/4 +1/6) =5/12 Remaining part of cistern= 1 - 5/6 =1/6 Pipe A can fill 1/4 part of the cistern in 1 minute,and can fill 1/6 part of the cistern in = 4*(1/6) =2/3 minutes Total time taken to fill the Cistern = time taken to fill (5/6 part + 1/6 part) |

Pipe A can fill a tank in 45 hrs and pipe B can fill it in 36 hrs. If both the pipes are opened in the empty tank. In how many hours will it be full? |

A) 10 hr B) 15 hr C) 20 hr D) 28 hr Correct Answer :20 hr Explanation :If a pipe can fill a tank in x hours, then : part filled in 1 hour = 1/x Part filled A in 1 hr= (1/45) |

If a pipe fills a tank in 6 h, then what part of the tank will the pipe fill in 1 h? |

A) 1/3 B) 1/6 C) 1/4 D) 1/5 Correct Answer :1/6 Explanation :If a pipe can fill a tank in x hours, then : part filled in 1 hour = 1/x Then,when a pipe fills a tank in 6 h, then the part of tank filled in 1 h = 1/6 |

A tap can fill a tank in 16 minutes and another can empty it in 8 minutes. If the tank is already half full and both the taps are opened together, the tank will be ? |

A) Filled in 12 min B) Emptied in 12 min C) Filled in 8 min D) Emptied in 8 min Correct Answer :Emptied in 8 min. Explanation :If a pipe can fill a tank in x hours and another pipe can empty the full tank in y hours (where x > y), then on opening both the pipes, the net part emptied in 1 hour = (1/y)-(1/x) = (1/8 - 1/16) = 1/16 |

One tap can fill a cistern in 2 hours and another can empty the cistern in 3 hours. How long will they take to fill the cistern if both the taps are opened ? |

A) 5 hours B) 6 hours C) 7 hours D) 8 hours Correct Answer :6 hours Explanation :If a pipe can .fill a tank in x hours and another pipe can empty the full tank in y hours (where y> x), then on opening both the pipes, the net part filled in 1 hour = (1/x)-(1/y) = (1/2 - 1/3) = 1/6 |