Question

There are infinite pipes attached to a very big tank. Pipes are numbered like P1,P2,P3………… and so on. Its also known that efficiency of every subsequent pipe is half the efficiency of earlier pipe, i.e., efficiency of P2 pipe is half the efficiency of P1 pipe and so on. However, in case of P1 pipe, this rule is not true since there is no earlier pipe. When all the pipes are working together, the tank gets filled in 2 hours.​

Answer 1

Answer:

Pipe A fills a tank of 700 litres capacity at the rate of 40 litres a minute. Another pipe B fills the same tank at the rate of 30 litres a minute. A pipe at the bottom of the tank drains the tank at the rate of 20 litres a minute. If pipe A is kept open for a minute and then closed and pipe B is kept open for a minute and then closed and then pipe C is kept open for a minute and then closed and the cycle repeated, how long will it take for the empty tank to overflow?

(1) 42 minutes (2) 14 minutes (3) 39 minutes (4) 40 minutes 33 seconds (5) None of these

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