"If you are not willing to learn, no one can help you learn. If you are determined to learn, no one can stop you."
There are four men who want to cross a bridge. They all begin on the same side. You have 17 minutes to get all of them across to the other side. It is nighttime, there is one torch. A maximum of two people can cross at one time. Any party who crosses, either one or two people, must have the torch with them. The torch must be walked back and forth, it cannot be thrown, etc. Each man walks at a different speed. A pair must walk together at the rate of the slower man.
Man 1: 1 minute to cross
Man 2: 2 minutes to cross
Man 3: 5 minutes to cross
Man 4: 10 minutes to cross
For example, if Man 1 and May 4 walk across first, 10 minutes have elapsed when they get to the other side of the bridge. If Man 4 returns with the torch, a total of 20 minutes have passed, and you have failed the mission.