A) 9 h
B) 18 h
C) 20 h
D) \[20\frac{1}{2}\]h
Correct Answer: C
Solution :
According to the question, Cistern can be filled in 1 h \[=\frac{1}{5}\] part Cistern can be emptied in 1 h\[=\frac{1}{4}\]Part When the both pipes are opened, simultaneously Cistern can be emptied in 1 h \[=\frac{1}{4}-\frac{1}{5}=\frac{5-4}{20}=\frac{1}{20}\]part \[\therefore \]The time in which it will be emptied = 20 hYou need to login to perform this action.
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