Two pipes P and Q would fill an empty cistern in 24 minutes and 32 minutes respectively.Both the pipes being opened together,find when the first pipe must be turned off so that the empty cistern may be just filled in 16 minutes.

A cistern can be filled by two pipes in 30 and 40 min respectively. Both the pipes are opened at once, when the first pipe must be turned off so that the tank may be just filled in 18 min?

Two inlet pipes A and E can fill an empty cistern in 12 minutes and 36 minutes respectively. Both the pipes A and E are opened together and after some time pipe A is closed. If the cistern gets filled in 20 minutes, then for how many minutes pipe A was open?

Two pipes P and Q can fill a cistern in 15 minutes and 20 minutes respectively. Both are opened together, but at the end of 5 minutes, the pipe P is turned off. How long will the pipe Q take to fill the cistern ?

Two pipes P and Q can fill a cistern in 15 minutes and 20 minutes respectively. Both are opened together, but at the end of 5 minutes, the pipe P is turned off. How long will the pipe Q take to fill the cistern ?