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Several boxes together weigh 10 tons, and each of them weighs no more than one ton. How many three-ton trucks are definitely enough to haul this cargo?

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We will load the trucks with boxes in any order, only ensuring that the "overloading" of the truck does not occur. As a result, more than 2 tons will be loaded onto each truck. Therefore, five trucks will definitely be enough. Four trucks may not be enough. For example, let's say we have 13 boxes, each weighing ${ }^{10} / 13$ tons. Then one truck can carry no more than three such boxes (4 boxes weigh more than 3 tons), and all four trucks will carry no more than 12 boxes.

## Otvet

5 three-ton trucks