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Two pipes A and B can fill a cistern in 20 min and 25 min respectively. Both the pipes are opened together but at the end of 5 min, the first is turned off. How long does it take to fill the cistern? |
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Answer» Let it take x minutes to fill the cistern, then work done by (Pipe A in 5 min. + Pipe B in x min.) = 1 \(\Rightarrow\) \(\frac{5}{20}\)+ \(\frac{X}{25}\)= 1 \(\Rightarrow\) \(\frac{25+4X}{100}\) = 1 \(\Rightarrow\) 25 + 4x = 100 \(\Rightarrow\) 4x = 75 \(\Rightarrow\)x = 18.75 min |
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