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- Two taps can fill a cistern in 30 and 40 minutes respectively.
Question 1:
Two taps can fill a cistern in 30 and 40 minutes respectively. If both the taps are opened simultaneously then the approximate time taken to fill the cistern is: A. 17 minutes
Feedback Remember the shortcut method:
'Two pipes A and B can fill (or empty) a tank in X and Y minutes respectively, while working alone. If both the pipes are opened together, then the time taken to fill (or empty) the cistern is given by XY/(X+Y) minutes.'
Here, X = 30 minutes and Y = 40 minutes
Therefore, the required time = 30 x 40 /(30 + 40) = 1200/70 = 120/7 = 17 1/7 minutes.
Hence the answer is 17 minutes (approximately)
'Two pipes A and B can fill (or empty) a tank in X and Y minutes respectively, while working alone. If both the pipes are opened together, then the time taken to fill (or empty) the cistern is given by XY/(X+Y) minutes.'
Here, X = 30 minutes and Y = 40 minutes
Therefore, the required time = 30 x 40 /(30 + 40) = 1200/70 = 120/7 = 17 1/7 minutes.
Hence the answer is 17 minutes (approximately)
B. 12 minutes
C. 19 minutes
D. 21 minutes
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