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Maths23xp
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There are 20 questions.

8 questions will appear in an exam.

I must choose 3 of those 8 questions to answer in the exam.

I have 2 weeks to prepare.




What is the minimum amount of questions I must revise in order to ensure I can answer 3 of these questions in the exam?
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googie3
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The minimum number of questions you must revise over the two weeks is 20 since any 8 of the 20 questions can appear and you can do any 3 of them.
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Notnek
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(Original post by Maths23xp)
There are 20 questions.

8 questions will appear in an exam.

I must choose 3 of those 8 questions to answer in the exam.

I have 2 weeks to prepare.




What is the minimum amount of questions I must revise in order to ensure I can answer 3 of these questions in the exam?
I think you can work this out yourself. E.g. if you revise 10 of the questions then all 8 questions could be ones that you haven't revised. So that wouldn't guarantee it.

What about 11, 12, etc.?
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Maths23xp
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(Original post by googie3)
The minimum number of questions you must revise over the two weeks is 20 since any 8 of the 20 questions can appear and you can do any 3 of them.
I am sure that is not right.

I think the answer is 15.

If I revise 15 questions - and 5 of the questions I HAVE NOT revised appear in the exam, that will leave 3 questions left which I will have revised (8 questions in total).
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Maths23xp
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(Original post by Notnek)
I think you can work this out yourself. E.g. if you revise 10 of the questions then all 8 questions could be ones that you haven't revised. So that wouldn't guarantee it.

What about 11, 12, etc.?
I think the answer is 15.

If I revise 15 questions - and 5 of the questions I HAVE NOT revised appear in the exam, that will leave 3 questions left which I will have revised (8 questions in total). It is these 3 questions which I must answer.
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Notnek
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(Original post by googie3)
The minimum number of questions you must revise over the two weeks is 20 since any 8 of the 20 questions can appear and you can do any 3 of them.
That's not right. E.g. if they revise 19 questions then even if that 1 question that they didn't revise comes up in the 8, they only have to choose 3 so it would be guaranteed that they have revised enough questions.
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Notnek
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(Original post by Maths23xp)
I think the answer is 15.

If I revise 15 questions - and 5 of the questions I HAVE NOT revised appear in the exam, that will leave 3 questions left which I will have revised (8 questions in total). It is these 3 questions which I must answer.
Yes that's correct if you want to guarantee that you have revised enough questions. If you want to ensure with a high percentage (as opposed to 100%) then the question becomes a bit harder
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