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    Could somebody possibly check over this for me? I thought my method was correct but it's the first question on a past paper and they normally give 'nicer' values for the answer (not sure how to phrase that sorry!) which specifically appear in the tables so now I'm doubting it.

    Question:
    Y is normally distributed with mean \mu and standard deviation 2.50. Given that P(Y>12) = 0.3 find the value of \mu.

    I've done:
    P(Z < \frac{12 - \mu}{2.5}) = 0.7
    From the normal tables, \frac{12 - \mu}{2.5} = 0.52433?

    Rearrange to get \mu = 10.7 to 3sf.

    Thank you!
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    (Original post by olivia30)
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    looks good to me are you edexcel for maths?
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    (Original post by olivia30)
    ...
    What normal tables are you using? I haven't seen ones in the formula booklet with that much accuracy, are you on OCR or something? :eek:
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    (Original post by Zacken)
    What normal tables are you using? I haven't seen ones in the formula booklet with that much accuracy, are you on OCR or something? :eek:
    (Original post by DylanJ42)
    looks good to me are you edexcel for maths?
    Thanks both of you! I'm OCR. My tables gave me p(0.524)=0.6999 so I used linear interpolation (is that what it's called) to get the .33 on the end. Not really necessary since they only ask for answers to 3sf but oh well :h:
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    (Original post by olivia30)
    Thanks both of you! I'm OCR. My tables gave me p(0.524)=0.6999 so I used linear interpolation (is that what it's called) to get the .33 on the end. Not really necessary since they only ask for answers to 3sf but oh well :h:
    its no problem

    ah i see, well if youre taught to use interpolation for these scenarios then you're definitely right
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    (Original post by Zacken)
    What normal tables are you using?
    In case you're really interested (which I'm sure you're not :lol:):
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    (Original post by olivia30)
    In case you're really interested (which I'm sure you're not :lol:):
    ...I'm worse than you think. I went and googled it myself half an hour ago, it's the same formula booklet I use for STEP! :lol:
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    (Original post by Zacken)
    ...I'm worse than you think. I went and googled it myself half an hour ago, it's the same formula booklet I use for STEP! :lol:
    Don't worry, I googled the Edexcel one to see the difference! :laugh: Yours is divided into specific C1, C2 etc sections! :eek: Jealous. assuming you're Edexcel, that is.

    (Original post by DylanJ42)
    its no problem

    ah i see, well if youre taught to use interpolation for these scenarios then you're definitely right
    Good to know, thank you!
 
 
 
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