There are five water pipes P_1 P_2, P_3, P_4,P_5 connected to a tank, which can fill or empty the tank individually in 45, 40,30,20,15 minutes, respectively. A few of them are inlet pipes and others are the outlet pipes. If the combination of an inlet pipe and an outlet pipe can either empty or fill the whole tank in 1 hour, which one of the following can be the feasible combination of pipes as indicated by {inlet pipe, outlet pipe} in that order only?

There are five water pipes P_1 P_2, P_3, P_4,P_5 connected to a tank,

1.	There are five water pipes P_1 P_2, P_3, P_4,P_5 connected to a tank, which can fill or empty the tank individually in 45, 40,30,20,15 minutes, respectively. A few of them are inlet pipes and others are the outlet pipes. If the combination of an inlet pipe and an outlet pipe can either empty or fill the whole tank in 1 hour, which one of the following can be the feasible combination of pipes as indicated by {inlet pipe, outlet pipe} in that order only?
Answer» `{P_3,P_4}` and `{P_4,P_5}` `{P_1,P_2}` and `{P_4,P_5}` `{P_4,P_3}` and `{P_5,P_4}` `{P_4,P_3}` and `{P_4,P_5}` ANSWER :D