Question

Two pipes A and B can fill a cistern in 12 and 15 minutes respectively. If both are opened together and at the end of 3 minutes, pipe A is closed, how much longer will the cistern take to fill?

5 minutes
814 minutes
812 minutes
834 minutes​

Answer 1

Answer:

Part filled in 5 min =5×(121+151)

=5×609=43

Part emptied in 1 minute when all the pipes are opened =61−(121+151)=601.

Now, 601part is emptied in 1 minute.

Therefore, 43 part will be emptied in 60×43=45 minutes.

This just same as above question.