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# Statistics 3 Edexcel normal distribution accuracy Watch

1. Hi, I want to ask regarding to the accuracy required in the exam of Statistics 3, Edexcel. Because in the formula booklet, sometimes, a certain value does not give you the probability or z in the required accuracy. So I wonder if it matters? (In the mark scheme, they always use values of 4 decimal places, but that value is not in the booklet). So where do I get those values?
2. (Original post by Geraer1)
Hi, I want to ask regarding to the accuracy required in the exam of Statistics 3, Edexcel. Because in the formula booklet, sometimes, a certain value does not give you the probability or z in the required accuracy. So I wonder if it matters? (In the mark scheme, they always use values of 4 decimal places, but that value is not in the booklet). So where do I get those values?
Im not sure what you mean but i will clarify what i think you mean.

Sometimes in the mark scheme they get a Z value with loads of decimal places, this is usually done by calculation using integral. You don't need to do this, your expected to get a Z value with 2 or 4(if your using the small table) decimal places from the table. They put a value such as 1.12318273... for examiners so that they can recognize integral answers.

Also, if your working out the Z value yourself, you are required to round it to 2 decimal places so that you can use the table. Example if you calculate a Z value of 2.13458 then you use 2.13.

Hope this helps, if it doesn't, i'll be happy to help again if you clarify your question with examples.
3. (Original post by Inges)
Im not sure what you mean but i will clarify what i think you mean.

Sometimes in the mark scheme they get a Z value with loads of decimal places, this is usually done by calculation using integral. You don't need to do this, your expected to get a Z value with 2 or 4(if your using the small table) decimal places from the table. They put a value such as 1.12318273... for examiners so that they can recognize integral answers.

Also, if your working out the Z value yourself, you are required to round it to 2 decimal places so that you can use the table. Example if you calculate a Z value of 2.13458 then you use 2.13.

Hope this helps, if it doesn't, i'll be happy to help again if you clarify your question with examples.
Yeah really thanks with your response! I have solved this problem now, well the reason why sometimes they have 4 decimal places is because there is another table in the Edexcel formula booklet after the normal distribution one which gives you that.
4. (Original post by Geraer1)
Yeah really thanks with your response! I have solved this problem now, well the reason why sometimes they have 4 decimal places is because there is another table in the Edexcel formula booklet after the normal distribution one which gives you that.
Oh right, the bigger than table! Okay xD
5. Oh yeah, I answered this yesterday. Try not to make duplicate posts.

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