sneha try one more question it is so much easy
A pipe P,can fill an empty tank in 12 min and another pipe Q, can empty same tank in 20 min. Pipe P is configured to close automatically when the water level reaches in the tank reaches 3/4th of the height of the tank and simultaneously the pipe Q opens and operates until the water level fall to exactly 1/4th of the height of the tank after which it closes and simultaneously P opens. If this process continues indefinitely, what portion of the tank is filled after excatly one hour?(assume that tank is initially empty)
