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anonymous

  • one year ago

Hey guys, I really need help! Will fan and medal :) Scores on a statewide standardized test are normally distributed with a mean of 12.89 and a standard deviation of 1.95. Certificates are given to students whose scores are in the top 2% of those who took the test. This means that they scored better than 98% of the other test takers. Marcus received his score of 13.7 on the exam and is wondering why he didn’t receive a certificate. Show all work to determine whether Marcus’ score was high enough to earn a certificate. Write Marcus a letter about why he didn't recieve a certificate.

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  1. anonymous
    • one year ago
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    Oh, and include a brief summary of your statistical analysis in your letter. :) Almost forgot.

  2. Vocaloid
    • one year ago
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    his score is 13.7, the mean is 12.89, and the standard deviation is 1.95 convert his score to a z-score using the formula z-score = (given value - mean)/standard deviation then, use your calculator to determine the percentage of data values that fall below mark's score (normalcdf(-99, marks score)). if this value is greater than 0.98, then that means that Mark is in the top 2%. Otherwise, Mark is not in the top 2%.

  3. Vocaloid
    • one year ago
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    small correction: normalcdf(-99, marks z-score)

  4. anonymous
    • one year ago
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    So the z-score would be 13.7 - 12.89/1.95?

  5. Vocaloid
    • one year ago
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    parentheses

  6. anonymous
    • one year ago
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    So (13.7 - 12.89)/1.95?

  7. Vocaloid
    • one year ago
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    yes

  8. anonymous
    • one year ago
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    Now, I'm kind of confused about finding the marks below Marcus' score...

  9. Vocaloid
    • one year ago
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    normalcdf(-99, marcus' z-score) I meant to say "Marcus", not "Mark")

  10. anonymous
    • one year ago
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    Sorry, the data points below Marcus' score

  11. Vocaloid
    • one year ago
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    what is normalcdf(-99, marcus' z-score)?

  12. anonymous
    • one year ago
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    What does normalcdf mean?

  13. Vocaloid
    • one year ago
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    do you know how to use a graphing calculator?

  14. anonymous
    • one year ago
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    Umm, no... But I have a regular scientific one

  15. anonymous
    • one year ago
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    I don't need one for what I'm doing... Maybe... I'm not sure lol :P

  16. Vocaloid
    • one year ago
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    hm, did your teacher show you how to use a z-table?

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  17. anonymous
    • one year ago
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    Yes :) I have a z-table for positive and negative values.

  18. Vocaloid
    • one year ago
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    great! Marcus' z-score is 0.415, do you know how to use the z-table to find the area to the left of the z-score?

  19. anonymous
    • one year ago
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    I think so. Is it .65910?

  20. Vocaloid
    • one year ago
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    yup, that's about what I got, too! do you know what .65910 means?

  21. Vocaloid
    • one year ago
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    I mean, do you understand what that number represents?

  22. anonymous
    • one year ago
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    It means that he falls in with the scores of %65.9 of his class?

  23. Vocaloid
    • one year ago
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    not quite, it means that he scored better than 65.9% of the other students in order for Marcus to be in the top 2% and get the certificate, he needs to score better than 98% of all the other students so, do you think he got the certificate?

  24. anonymous
    • one year ago
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    Ooh, ok! :) Nope, he didn't.

  25. Vocaloid
    • one year ago
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    great, we've answered the question! good job

  26. anonymous
    • one year ago
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    Yay! Thank you so much @Vocaloid

  27. anonymous
    • one year ago
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    I fanned and medaled :)

  28. Vocaloid
    • one year ago
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    thanks, I really appreciate it ^ ^

  29. anonymous
    • one year ago
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    Np :) ttyl!

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