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ShortChallenge Level Yellow star
Secondary curriculum
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If the witch is guessing, then in the long term, half of the time she will get it right.

So half of the time, she will keep £100, and half of the time, she will have to give the £100 back and pay £50 compensation.

So half of the time, she will make £100. The other half of the time she will lose £50.

This means that after 100 babies have been born, she can expect to have gained £5000 and paid out £2500, so she will be £2500 in profit.



You can find more short problems, arranged by curriculum topic, in our short problems collection.

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Connect Three

In this game the winner is the first to complete a row of three. Are some squares easier to land on than others?

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Can you work out which spinners were used to generate the frequency charts?

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The NRICH Project aims to enrich the mathematical experiences of all learners. To support this aim, members of the NRICH team work in a wide range of capacities, including providing professional development for teachers wishing to embed rich mathematical tasks into everyday classroom practice.

NRICH is part of the family of activities in the Millennium Mathematics Project.

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