时间成谜

We discussed Artificial Intelligence this evening. Kerry showed us some videos such as The Terminator, Transformers and I, Robot to explain AI in Hollywood and one sample from discovery channel to show AI technology in the real world.
Compared with robot, pattern recognition is a part of AI which is much closer to our daily life. We may use fingerprint identifier to unlock a laptop, use writing pad and speech recognition software to input  information. Once I have interviewed a company who used fingerprint identification technology in its  HR system.

Finally, Kerry left us some questions.
1、You have 2 jars, one with 50 red beans inside and another with 50 green ones. There is someone who will pick up 1 bean from your 2 jars. What shall you do to make him much easier to pick a red one out?

2、There are 4 people in front of a bridge over river. It takes 1 minute for A to walk through this bridge. B needs 2 minutes, C needs 5 and D needs 10. Only 2 persons can walk on the bridge at the same time and they must move at the speed of the slower one. 4 people only have 1 torch which is necessary when walking across the bridge. How can they move as quickly as possible?