A community for students.

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

AnimalLover8

  • one year ago

The time required to finish a test in normally distributed with a mean of 80 minutes and a standard deviation of 15 minutes. What is the probability that a student chosen at random will finish the test in more than 95 minutes?

  • This Question is Closed
  1. AnimalLover8
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    82% 2% 34% 16%

  2. jim_thompson5910
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    Do you have a TI calculator?

  3. AnimalLover8
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    No, if I did I would be able to do many more questions.

  4. jim_thompson5910
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    ok we'll use a table then

  5. jim_thompson5910
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    first convert the raw score x = 95 to a z-score use the formula z = (x-mu)/sigma

  6. jim_thompson5910
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    in this case, mu = 80 and sigma = 15

  7. AnimalLover8
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    What is the "raw score"?

  8. jim_thompson5910
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    x = 95 is the raw score

  9. jim_thompson5910
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    it's the score on the test the z-score is the transformed score to the standard normal distribution

  10. jim_thompson5910
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    z = (x-mu)/sigma z = (95-80)/15 z = ???

  11. AnimalLover8
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    So z=...1?

  12. jim_thompson5910
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    yes z = 1

  13. jim_thompson5910
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    ie, z = 1.00

  14. jim_thompson5910
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    Now use a table like this one https://www.stat.tamu.edu/~lzhou/stat302/standardnormaltable.pdf locate the row that starts with `1.0` and find the column that has `.00` at the top the intersection of this row and column has the number ______ (fill in the blank)

  15. AnimalLover8
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    .84134

  16. AnimalLover8
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    I don't understand what this number actually is.

  17. jim_thompson5910
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    this number represents the probability of getting a z-score less than 1.00 in notation form, we say `P(Z < 1.00) = 0.84134` so there's approx a 84.134 % of getting a z-score less than 1.00 in other words, there is a 84.134 % chance of getting a test score less than 95

  18. jim_thompson5910
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    subtract 0.84134 from 1 to get the probability of getting a score larger than z = 1 or x = 95

  19. AnimalLover8
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    0.269... ?

  20. jim_thompson5910
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    compute 1 - 0.84134

  21. AnimalLover8
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Wait so how do you get the probability from there?

  22. jim_thompson5910
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    1 - 0.84134 = 0.15866

  23. jim_thompson5910
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    0.15866 = 15.866% which rounds to 16%

  24. jim_thompson5910
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    we have some normal curve |dw:1440808310147:dw|

  25. AnimalLover8
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    OOOOOOH!

  26. jim_thompson5910
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    |dw:1440808329487:dw|

  27. jim_thompson5910
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    |dw:1440808367344:dw|

  28. AnimalLover8
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Yeah. :) Thank you so much!

  29. jim_thompson5910
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    I'm glad that everything is making sense now

  30. AnimalLover8
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Me too, I usually pick things up very quickly, but I just couldn't hack this question. :)

  31. Not the answer you are looking for?
    Search for more explanations.

    • Attachments:

Ask your own question

Sign Up
Find more explanations on OpenStudy
Privacy Policy

Your question is ready. Sign up for free to start getting answers.

spraguer (Moderator)
5 → View Detailed Profile

is replying to Can someone tell me what button the professor is hitting...

23

  • Teamwork 19 Teammate
  • Problem Solving 19 Hero
  • You have blocked this person.
  • ✔ You're a fan Checking fan status...

Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.

This is the testimonial you wrote.
You haven't written a testimonial for Owlfred.