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Statistics 2 - Sampling watch

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    OCR S2 question coming up but before that quick question:

    a) When sampling do you only continuity correct questions that have been or need to be approximated to another distribution? Or do I have to 1/2n all Sampling questions?

    b) The proportion of faulty cups made by a factory machine is 0.08. The cups, including faulty ones, are packed in boxes of 100. About 4000 cups are required for an outdoor concert and the manager orders 44 boxes. Find the probability that these boxes will provide more than 4000 perfect cups.

    b) answer) 0.9957
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    a)
    You only use the continuity correction when estimating a probability from a discrete distribution to a continuos distribution.
    e.g. P(x<50) in a discrete distribution = P(z<50.5) in a continous one
    P(x<=50) in discrete = P(z<49.5) in continous

    b)
    I'm not sure on this one, it could be binomial
    X~B(100,0.08) X = number of faulty cups
    mean = 8
    variance = 7.36

    44X(4400,0.08)
    X~Po(352)
    P(X>4400), havent got tables to work out, may be able to use normal to estimate

    I think that may be it although it has been some time
 
 
 

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