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Homework Help: Percentiles and Z- Scores

  1. Oct 17, 2004 #1
    Hi i am having trouble with a couple questions involving percentiles, here is the question:

    1) Adrian's average bowling score is 174, with a standard deviation of 35.
    a) In what percent of games does Adrian score less than 200 points? More than 200 points?
    b) The top 10% of bowlers in Adrian's league get to play in an all-star game. If the league average is 170, with a standard deviation of 11 points, what average score does Adrian need to have to obtain a spot in the all-star game?

    Thank you.
  2. jcsd
  3. Oct 17, 2004 #2


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    Science Advisor
    Homework Helper

    Use the definition of Z-score:

    [tex]Z = \frac {x - \bar x}{\sigma}[/tex]

    and use your textbook tables for cumulative probability (or words to that effect depending on the authors).
  4. Oct 18, 2004 #3
    I figured it out now, you had to use this Z-score table in the back of the text book which i did not know how to do. Thanks for the help though.
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