Three pipes A, B and C can fill a tank in 6 hours, 9 hours and 12 hours respectively. B and C are opened for half an hour, then A is also opened. The time taken by the three pipes together to fill the remaining part of the tank is -

A tap drips at a rate of one drop/second. 600 drops make 100 ml. The number of liters wasted in 300 days is -