During the gasoline transporting from one plant to another, the fuel tanker ever wasted 10 liters of gasoline. The process of filling the tank at one plant and discharge of gasoline from its bottom at another is monitored very carefully.
All holes of fuel tanker were thoroughly filled, and it was accompanied by a reliable guard during their journey. But still, the discharge of fuel always lacked exactly 10 liters.
Where did the petrol disappeare?