A community for students.

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

anonymous

  • 5 years ago

An experiment consists of 48 binomial trials, each having probability 3/4 of success. Use an approximating normal curve to estimate the following probabilities. (a) between 35 and 39 successes, inclusive.

  • This Question is Closed
  1. anonymous
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    use the fact that when np>5, then a normal approximation with mean np and std. dev with sqrt(np(1-p)) allows you to solve this. So, the normal curve with mean 36 and std. dev. of 3 will be what you need to use

  2. anonymous
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    yea i found all those already. n= 48 p = .75 mean = 36 st. dev. = 3 I tried 36.5-36/3 but the answer I got was wrong.... I don't know what I'm doing wrong.

  3. anonymous
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    oops not 36.5-36 that's for another question. Ignore the bottom part.

  4. anonymous
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    I guess I should say, you should then use 35<x<39 and then find the area between the z curves (x-u)(sigma)...don't know sigma symbol. sorry

  5. anonymous
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    I thought I would do 35 - 36/3 and 39-36/3 but that's wrong too. I'm not sure what I'm doing.

  6. anonymous
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    35-36=-1, then divide by 3 is -1/3 39-36=3 then divide by 3 is 1

  7. anonymous
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    those are the z-values you want to use...Is that still giving you the wrong answer?

  8. anonymous
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    should be around 47% or so yes?

  9. anonymous
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    I know I got those answers, but when I subtracted the area of those...it was still wrong. .8413-.3821 = .4592

  10. anonymous
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Still not right....

  11. anonymous
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    what is the answer? maybe they want you to use a continuity correction

  12. anonymous
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    I don't know the answer, they won't give it to me. I have to keep on trying until I get it right.

  13. anonymous
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    hmm, that is strange. if you get really desperate you could always sum up the bernoulli cases 35, 36, 37, 38, and 39 if you have access to technology that computes combinations

  14. anonymous
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Yes I have a TI-83. How would I do that? 35C0 + 36C.....those?

  15. anonymous
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    48C35*p^35*(1-p)^13+48C36*p^36*(1-p)^12+...

  16. anonymous
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    .5795 is what I got

  17. anonymous
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    if you use continuity corrections, then you get this answer. I had forgot to do that. when you go from a discrete to a continuous probability, this can sometimes greatly affect your answer, especially when bounded on both sides

  18. anonymous
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    .5795 is incorrect too... Thanks for trying to help me though!

  19. anonymous
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    man, that is crazy,I'm a stats man and this is embarrassing ;( is it a computer system? then maybe it is rejecting due to rounding, you think?

  20. anonymous
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    with continuity correction i got around .57. other than that, I got nothing...though this problem will bother me for a while!

  21. anonymous
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    I tried .5795, .57, and .58. None of them worked. I have been working on this problem for a while now haha so it's okay. Thank you for trying to help me with this though! I have another question though if you still want to help me? The third part of the question asks me to find "more than 36 successes" I did 36.5-36 / 3 which = .1666, so the area would be .5636 but that's incorrect. What am I doing wrong?

  22. anonymous
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    greater than means you have to take 1-minus the value from the z-score

  23. anonymous
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    the z-table gives you less than percentage, not greater than percentage

  24. anonymous
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Which would make it .4364 ..... which is still wrong...

  25. anonymous
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    I feel like I'm making a silly mistake.

  26. anonymous
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    hmm, I just don't know why it isn't working out. that is definitely what you are supposed to do when you have a bernoulli problem and are using the normal curve to approximate it. I really don't know what to tell ya. did you try this one without the cont. correction? it would be 50%. If that doesn't work then I really have no idea:(

  27. anonymous
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    actually, more than 36 without cont.correction would be 37, which would give 1/3 and then 1-that would be around .367...I have no clue at this point though. wish you luck

  28. anonymous
    • 5 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    :( Okay well thank you for helping me!

  29. 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.