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anonymous

  • one year ago

Statistics Algebra 2 help !

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  1. anonymous
    • one year ago
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    The grades on the last science exam had a mean of 89%. Assume the population of grades on science exams is known to be distributed normally, with a standard deviation of 14%. Approximately what percent of students earn a score between 75% and 89%?

  2. anonymous
    • one year ago
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    Help please @jim_thompson5910 @amistre64 @Mertsj @SolomonZelman @iGreen @jdoe0001 @Nnesha @e.mccormick @Loser66 @Luigi0210 @ash2326 @surjithayer @KyanTheDoodle @oldrin.bataku @JoannaBlackwelder @Lady.Liv1776 ???

  3. amistre64
    • one year ago
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    hmm, id have to know what your material has covered so far

  4. amistre64
    • one year ago
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    and what you have to work the problem with

  5. amistre64
    • one year ago
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    it feels to me like an empirical rule approximation tho ...

  6. anonymous
    • one year ago
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    it is indeed, but im not sure how to use it

  7. amistre64
    • one year ago
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    well, determine how many deviations are between the mean and your end points

  8. amistre64
    • one year ago
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    what is our mean?

  9. anonymous
    • one year ago
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    89%

  10. amistre64
    • one year ago
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    and what is our left end point?

  11. anonymous
    • one year ago
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    75%

  12. anonymous
    • one year ago
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    with a standard deviation of 14%

  13. amistre64
    • one year ago
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    so, the difference between them is: what is 89-75?

  14. anonymous
    • one year ago
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    14

  15. amistre64
    • one year ago
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    which is exactly 1 standard deviation to the left of the mean. right?

  16. amistre64
    • one year ago
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    if we calculate the same with the other end point .. well, 89 to 89 is a difference of 0, so no standard deviations are to the right of the mean. what are your thoughts?

  17. anonymous
    • one year ago
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    I didnt get it, can you elaborate more?

  18. amistre64
    • one year ago
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    the only thing left to elaborate is what does the empirical rule state? it may be called something else in your material tho.

  19. amistre64
    • one year ago
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    and do we have options to choose from?

  20. anonymous
    • one year ago
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    68% will fall within the first standard deviation, 95%, the first two and 99.7 first three

  21. anonymous
    • one year ago
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    the options are: 38.5% 15.7% 50% 34.1%

  22. amistre64
    • one year ago
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    thats the rule yes, but it is better stated: within +- 1sd from the mean falls 68% of the data. 68/2 = 34 so 34% to the left (-1 sd), and 34% to the right (+1 sd) we know we are 1sd to the left, and 0 to the right ... what does that tell us?

  23. amistre64
    • one year ago
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    |dw:1437697237025:dw|

  24. anonymous
    • one year ago
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    I'm lost on this....

  25. amistre64
    • one year ago
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    it as plain as i can make it, you will have to tell me where it is losing you at.

  26. anonymous
    • one year ago
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    "within +- 1sd from the mean falls 68% of the data. 68/2 = 34 so 34% to the left (-1 sd), and 34% to the right (+1 sd) we know we are 1sd to the left, and 0 to the right ... what does that tell us?"

  27. anonymous
    • one year ago
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    I dont know what "that tell us"

  28. amistre64
    • one year ago
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    we determined how many standard deviations we are to the left of the mean, didnt we? 89-75 = ??

  29. anonymous
    • one year ago
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    14

  30. amistre64
    • one year ago
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    14 is the difference between the mean and the endpoint, and our standard deviation has a length of 14. what is 14/14?

  31. anonymous
    • one year ago
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    1

  32. amistre64
    • one year ago
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    so we are 1 sd to the left of the mean with that calculation. using the rule that you stated, or rather that i stated better: within +- 1sd from the mean falls 68% of the data. 68/2 = 34 so 34% to the left (-1 sd), and 34% to the right (+1 sd) we know we are 1sd to the left ... which gives us a value of ????

  33. anonymous
    • one year ago
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    ohh ok I think I get it

  34. anonymous
    • one year ago
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    the answer would be 34% of the students will get between 75 and 89

  35. amistre64
    • one year ago
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    we are 0 to the right of the mean so there is nothing to concern ourselves with over on that side ... so all in all, what would you say the answer chould be?

  36. anonymous
    • one year ago
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    34.1%

  37. amistre64
    • one year ago
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    thats what I would go with as well :)

  38. anonymous
    • one year ago
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    got it right thanks

  39. amistre64
    • one year ago
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    good luck

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