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    Hi, I was just wondering, if they give you Po(x) for the rate of something happening in a day, and then they ask you to find the p of it happening over a week, would you do Po(7x)?
    I ask this because the above is what i have been doing, however, in the exam style paper in the back of the book (question 4) they keep Po(3) - rate for 1 day, but just multiply it by 100 at the end (to find the p of it happening over 100 days).
    Isn't that incorrect? on example 6 page 25 (section 2.4) they clearly multiply the mean by 2 which is the change in the period of days.

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    I'd assume you're referring to parts b,c, and d of that question.

    For b, you find P(X=0). Then the question is asking for the expected number of days out of 100 when X=0. So just do 100P(X=0). Similar for the rest.
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    (Original post by valhalla92)
    I'd assume you're referring to parts b,c, and d of that question.

    For b, you find P(X=0). Then the question is asking for the expected number of days out of 100 when X=0. So just do 100P(X=0). Similar for the rest.
    ah okay, so if they asked for the probability out of 100 days, that's when you would multiply the mean by 100? but if they ask you for the number of days, you just calculate the probability for 1 day and multiply by 100?
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    (Original post by atofu)
    ah okay, so if they asked for the probability out of 100 days, that's when you would multiply the mean by 100? but if they ask you for the number of days, you just calculate the probability for 1 day and multiply by 100?
    Yes - the question wants how many vans for 100 one day periods.
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    thanks for the help you two :macarena:
 
 
 
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