###### Question 07 (General Aptitude)

Two pipes P and Q can fill a tank in 6 hours and 9 hours respectively, while a third pipe R can empty the tank in 12 hours. Initially, P and R open for 4 hours. Then P is closed and Q is opened. After 6 more hours R is closed. The total time taken to fill the tank (in hours) is _____.

(A) | 13.50 |

(B) | 14.50 |

(C) | 15.50 |

(D) | 16.50 |

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P & R open .so, part of tank filled==1/3

After 4 hrs P is closed and for 6 more hrs Q and R are opened so,part of tank filled==1/6

So. total tank filled in 10hrs==1/2

So. remaining half part is filled by Q alone

, t=4.5hrs

Total time taken to fill the tank=4+6+4.5=14.5 hrs (Ans)