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## '9 Weights' printed from http://nrich.maths.org/

You have been given 9 weights, one of which is slightly heavier
than the rest.

Can you work out which weight is heavier in just

two weighings of the balance?

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Can you

always work out
which weight is heavier in just

two weighings of the balance?

Could you

always work out
which is heavier in just two weighings if you had been given 10
weights?

You have now been given 27 weights, one of which is slightly
heavier than the rest. Can you work out which weight is heavier in
just

three weighings of the
balance?

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Can you

always work out
which weight is heavier in just

three weighings of the balance?

You now have 9 weights again, and know that one is a slightly
different weight, but you don't know if it is heavier or
lighter.

Can you work out which weight is different, and whether it is
heavier or lighter, in just

three
weighings ?

Can you explain how you would

always be able to tell in just

three weighings ?

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Could you

always work out
which is the odd one out in just three weighings if you had been
given 10 weights?