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Thread: Standard deviation comparison question

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    Standard deviation comparison question




    Two college roommates have each committed to donating to charity each week for the next year. The roomates' weekly incomes are independent of each other. Suppose the amount donated in a week by one roommate is approximately normal with mean $30 and standard deviation $10, and the amount donated in a week by the other roommate is approximately normal with mean $60 and standard deviation $200. Which of the following is closest to the expected number of weeks in a 52-week year that their combined donation will exceed $120?

    (A) 0; the combined donation never exceeds $120 in a week
    (B) 1 week
    (C) 3 weeks
    (D) 5 weeks (answer)
    (E) 8 weeks

    from a released AP Stat. multiple choice. Thank you!

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    Re: Standard deviation comparison question


    Hi! We are glad that you posted here! This looks like a homework question though. Our homework help policy can be found here. We mainly just want to see what you have tried so far and that you have put some effort into the problem. I would also suggest checking out this thread for some guidelines on smart posting behavior that can help you get answers that are better much more quickly.

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