Fraser sets the scene by asking Jay to imagine a bridge cloaked in darkness at nighttime. There are four people who need to cross this bridge, but they only have one flashlight. This flashlight needs to be used each time someone crosses the bridge, and a maximum of two people can be on the bridge at any one time. To demonstrate this puzzle, Fraser has four chess pieces. Each piece represents one of the people to cross the bridge.
Every person travels at a different rate of speed.
One person takes 10 minutes to cross the bridge, one person takes five minutes to cross the bridge, one person takes two minutes to cross the bridge and the last person takes one minute to cross the bridge. If two people travel across the bridge together, they must go at the rate of the slowest person. He also gives us a hint and says that the correct answer is NOT 19 minutes. Canada Inc. Discovery Canada 2000. All Rights Reserved.