Crossing the bridge
"U2" has a concert that starts in 17 minutes and they must all cross a bridge to get there. All four men begin on the same side of the bridge.You must help them across to the other side. It is night. There is one flashlight. A maximum of two people can cross at one time. Any party who crosses, either 1 or 2 people, must have the flashlight with them. The flashlight must be walked back and forth, it cannot be thrown etc.
Each band member walks at a different speed. A pair must walk together at the rate of the slower man's pace:
Bono: 1 minute to cross Edge: 2 minutes to cross Adam: 5 minutes to cross Larry:10 minutes to cross
For example: if Bono and Larry walk across first, 10 minutes have elapsed when they get to the other side of the bridge. If Larry then returns with the flashlight, a total of 20 minutes have passed and you have failed the mission.
Note: There is no trick behind this. It is the simple movement of resources in the appropriate order. There are two known answers to this problem. This is based on a question Microsoft gives to all prospective employees.
Note: Microsoft expects you to answer this question in under 5 minutes! There are no tricks to this like meeting halfway or anything. Good luck.
Answer  

One solution is that;
A 2nd version is swapping Bono and Edge. 
