MathDB

On the table there are

2n

coins that look the same. It is known that

n

of them weigh 9 g. each, while the remaining

n

weigh 10 g. each. It is required to split the coins into

n

pairs with total weight of each pair 19 g. Prove that this can be done in less than

n

weighings using a balance without additional weights (the balance shows which pan is heavier or that their weight is equal).

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