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0. Two pipes Pand Q can fill a cistern in 12 minutes and 15 minutes respectivand at the end of 3 minutes, P is closed. How much longer will the cistem take tofill? |
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Answer» In such kind of questions, take the LCM of 12,15 i.e. 60. Assume 60 ltrs is the capacity of cistern.Now, the rate of filling for pipe P- 60/12 = 5 ltrs per min.the rate of filling for pipe Q- 60/15 = 4 ltrs per min So at the end of 3 mins, the cistern will have - 15 ltrs (From pipe P-5X3) +12 ltrs (From pipe Q-4X3) =27 ltrs At the end of 3 mins, cistern will have remaining capacity of33 ltrs (60 ltrs- 27 ltrs) As only pipe Q will fill the cistern = 33/4 = 8.25 mins =8 mins 15 seconds. |
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