Question
Time taken by pipe 'A' to fill a tank is 30 minutes.
When both pipes 'A' and 'B' are opened together, the tank gets filled in 10 minutes. Find the time taken by 'B' to fill the tank alone.Solution
Let the capacity of the tank be 60 litres (LCM of 30 and 10).
Efficiency of 'A' = (60/30) = 2 litres/minute
Combined efficiency of 'A' and 'B' = (60/10) = 6 litres/minute
Efficiency of 'B' = 6 - 2 = 4 litres/minute
Therefore, required time = (60/4) = 15 minutes
Hence, the answer is 15 minutes.
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