binomial distribution question query

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Lina_Amiour
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I really dont understand why they are working out p (x=12) and p(x>12), but not
p (x<12) they did p (x <11) instead. why?
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mqb2766
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Looks like a typo as they define and use it as the 12 outcomes 0,1,2, ...,,11 so it should be P(x<12)
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Lina_Amiour
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(Original post by mqb2766)
Looks like a typo as they define and use it as the 12 outcomes 0,1,2, ...,,11 so it should be P(x<12)
oh ok thank you. Would you mind helping me with one more question, a different one?
Its the practice question 1 - in the mark scheme they got k as 1/10 whereas I got 1/4. I don't know where I went wrong. I used the cumulative distribution function,
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mqb2766
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(Original post by Lina_Amiour)
oh ok thank you. Would you mind helping me with one more question, a different one?
Its the practice question 1 - in the mark scheme they got k as 1/10 whereas I got 1/4. I don't know where I went wrong. I used the cumulative distribution function,
Can you upload what you did.
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Lina_Amiour
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(Original post by mqb2766)
Can you upload what you did.
i dont have any storage left to upload the picture. is it ok if you just briefly explain how to do the question?
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mqb2766
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(Original post by Lina_Amiour)
i dont have any storage left to upload the picture. is it ok if you just briefly explain how to do the question?
Shouldn't be more than a oouple of lines. Just upload your attempt as text.
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Lina_Amiour
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(Original post by mqb2766)
Shouldn't be more than a oouple of lines. Just upload your attempt as text.
so i thought that X has to be 4 or less so I did P (X<=4) = 1 getting k as 1/4. so i really don't get how they got 1/10
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mqb2766
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(Original post by Lina_Amiour)
so i thought that X has to be 4 or less so I did P (X<=4) = 1 getting k as 1/4. so i really don't get how they got 1/10
P(x<=4) is not P(x==4).
Just sum the given probabilities?
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Lina_Amiour
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(Original post by mqb2766)
P(x<=4) is not P(x==4).
Just sum the given probabilities?
why sum them?
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mqb2766
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(Original post by Lina_Amiour)
why sum them?
Because P(X<=4) is the sum of each of the probabilities P(x==1) to P(x==4).
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Lina_Amiour
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(Original post by mqb2766)
Because P(X<=4) is the sum of each of the probabilities P(x==1) to P(x==4).
ohhhh i see i get it now. Thank you SO much you have been a GREAT help
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