1) According to the length of water connection time, the one with short water connection time is connected first, and the total waiting time is the shortest.

The shortest time is 1X4+2X3+3x2+4=20 minutes.

1 When people pick up the water, there are four people waiting, and so on. When the fifth man picked up the water, no one was waiting.

2) The method is the same as above.

The shortest time is 3X3+4X2+5=22 minutes.