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    In a random sample of 1000 body feathers from birds of this species, how many would the researcher expect to find with lengths more than 1 standard deviation from the mean? [4]

    Please explain in a way that is understandable , I really tried to understand I just don’t get the answer (317)
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    Is this normal distribution? If so it would be 1000 x P(X>1+s.d.)
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    (Original post by Radioactivedecay)
    Is this normal distribution? If so it would be 1000 x P(X>1+s.d.)
    And how much would the s.d be ?
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    (Original post by Radioactivedecay)
    Is this normal distribution? If so it would be 1000 x P(X>1+s.d.)
    It is 1 right ? The sd is 1
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    (Original post by Sammysammy99)
    In a random sample of 1000 body feathers from birds of this species, how many would the researcher expect to find with lengths more than 1 standard deviation from the mean? [4]

    Please explain in a way that is understandable , I really tried to understand I just don’t get the answer (317)
    Refer to the normal distribution diagram I posted on your other thread.

    If we are looking for feathers of lengths MORE than 1 standards deviation away, we are interested in the right-most and left-most portions of the distribution that are beyond \mu + \sigma and \mu - \sigma. By looking at the percentages, this is simply the case of obtaining the probability of having the feathers greater than of length 1+(1 s.d.) or less than 1-(1 s.d.) which is just 2(13.6% + 2.1% + 0.1%) = 31.6% or so.

    The rest is just applying it on the sample for the approximation.
 
 
 
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