KISS has a concert that starts in 17 minutes and they must all cross a cat walk to get to the stage. Unfortunately, the suspended platform they are standing on also happens to be a giant fire cannon that goes off at the first of the show and will kill anyone standing on it when it ignites. The catwalk has not been inspected for a very long time and when the cannon ignites, the catwalk will break away and anyone on it will die.

There is no way off the platform but by the catwalk.

The group has one flashlight. The Arena lights have just gone down. Only two people at a time can cross the catwalk and each time it is crossed, the flashlight must go along because of some dangerous, weak, and open spots in the catwalk. 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.

Gene: - 1 minute to cross
Paul: - 2 minutes to cross
Peter: - 5 minutes to cross
Ace: - 10 minutes to cross

For example: If Ace and Peter walk across first, 10 minutes have elapsed when they get to the other side of the catwalk to the stage. If Ace then returns with the flashlight, a total of 20 minutes have passed and Gene and Paul are incinerated by the cannon and Ace falls to his death from the catwalk.

Everything you need to know is provided. There is no trick involved. It is a specific sequence of movements that solves the riddle. There are two known answers to this problem.

Remember:

All 4 musicians are at the other side, on stage in 17 minutes when the fire cannon goes off.

2 guys at a time MAX on the catwalk at any time.

AND, they MUST have the ONE flashlight with them each time to cross the dangerous catwalk.