# Cars Across the Desert Puzzle - Solution

### The Puzzle:

A car has to carry an important person across the desert.

There is no petrol station in the desert and the car has space only for enough petrol to get it half way across the desert.

There are also other identical cars that can transfer their petrol into one another.

How can we get this important person across the desert?

There is no petrol station in the desert and the car has space only for enough petrol to get it half way across the desert.

There are also other identical cars that can transfer their petrol into one another.

How can we get this important person across the desert?

### Our Solution:

We need 4 cars (including the car with the important person).

All 4 cars start full.

At 1/6th of the way, all cars are 2/3rds full. One car sacrifices itself and fills up two of the other cars. Two cars are now full, one is 2/3rds full. (An empty car is left behind.)

At 2/6th of the way, two cars are 2/3rds full. One car is one third full, and sacrifices itself to fill up one of the other cars. One car is now full, one is 2/3rds full. (An empty car is left behind.)

At half way, one car is 2/3rds full. One car is one third full, and sacrifices itself to fill the other car, which is now full and can make the other half of the journey.

All 4 cars start full.

At 1/6th of the way, all cars are 2/3rds full. One car sacrifices itself and fills up two of the other cars. Two cars are now full, one is 2/3rds full. (An empty car is left behind.)

At 2/6th of the way, two cars are 2/3rds full. One car is one third full, and sacrifices itself to fill up one of the other cars. One car is now full, one is 2/3rds full. (An empty car is left behind.)

At half way, one car is 2/3rds full. One car is one third full, and sacrifices itself to fill the other car, which is now full and can make the other half of the journey.

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