Interview Q&A / Aptitude
Aptitude interview questions
Quantitative shortcuts for placement tests: percentages, time and work, and more.
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- Pipes A and B can fill a tank in 20 and 30 minutes. Both are opened, and after 5 minutes B is closed. How much longer does A take to fill the tank?
11 minutes 40 seconds. With 60 units: together they add 5 units a minute, so 25 units in 5 minutes. A then fills the remaining 35 units at 3 a minute, taking 35/3 = 11 2/3 minutes.
IntermediateQuick answer1 min read - Two pipes fill a cistern in 36 and 45 minutes. A waste pipe can empty it in 30 minutes. If all three are opened together, how long does the cistern take to fill?
60 minutes. With 180 units: the inlets add 5 and 4 a minute and the waste pipe removes 6, so the net is 3 units a minute and 180/3 = 60 minutes.
IntermediateQuick answer1 min read