A) 5 minutes
B) \[8\frac{1}{2}\] minutes
C) \[8\frac{1}{4}\]minutes
D) \[8\frac{3}{4}\] minutes
Correct Answer: C
Solution :
Part of the cistern filled by both pipes in 3 minutes \[=3\left( \frac{1}{12}+\frac{1}{15} \right)=3\left( \frac{5+4}{60} \right)=\frac{3\times 9}{60}=\frac{9}{20}\] Remaining part \[=1-\frac{9}{20}=\frac{11}{20}\] \[\therefore \] Time taken by pipe Q in filling \[\frac{11}{20}\] part \[=\frac{11}{20}\times 15=\frac{33}{4}\]minutes \[=8\frac{1}{4}\] minutesYou need to login to perform this action.
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