Quantcast

A community for students. Sign up today!

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

yashar806

  • one year ago

Who can help me with statistics?

  • This Question is Closed
  1. yashar806
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    1 Attachment
  2. SandeepReddy
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Yes!

  3. yashar806
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    can you help?

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

    Working on it

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

    Im afraid d00d

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

    Its taking time for me, Sorry 'bout that

  7. calmat01
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Sorry, statistics is out of my area...

  8. calmat01
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Yoou should probably try the statistics section.

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

    it was long ago that i studied stats, try in statistics section

  10. yashar806
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    nobody helps me in statistics section

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

    The average should be just (0.15) * 235

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

    @wio 15% of the PEOPLE are lefties, not 15% of the seats

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

    Okay I mean (0.15)*205

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

    \[ n = 205 \text{ trials (number of students)}\\ p = 0.15 \text{ probability}\\ -\\ \mu = np \text{ mean}\\ \sigma =\sqrt{np(1-p)} \text{ standard deviation} \]

  15. yashar806
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    what about the second one

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

    \[ \hat{p} = X/n \]

  17. yashar806
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    what is x and n?

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

    As I said before \(n\) is number of students. \(X\) is number of lefties.

  19. yashar806
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    27/235 ?

  20. yashar806
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    is that right?

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

    sorry I gotta go

  22. yashar806
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    please help me out

  23. yashar806
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    last one

  24. satellite73
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    isn't the mean just 15% of 205 ?

  25. yashar806
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    im not sure

  26. satellite73
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    yeah i am pretty sure that is what it is. i don't really know any statistics

  27. satellite73
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    oh i didn't look @wio wrote the answer above

  28. yashar806
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    so how should I find it

  29. satellite73
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    find the mean? it is \(.15\times 205=30.75\)

  30. satellite73
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    standard deviation is what @wio wrote as well

  31. yashar806
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    I don't understand last one

  32. satellite73
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    http://www.wolframalpha.com/input/?i=sqrt%28205*.15*.85%29

  33. satellite73
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    i guess you are to assume that it is normally distributed, so using a normal table find the probability that \(X<27\)

  34. yashar806
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    in this case should I use 235 or 205 ? for total?

  35. satellite73
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    or rather change to a z score, that is my guess

  36. satellite73
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    the 235 is not important. there are 205 students, the mean is \(30.75\) and the standard deviation is about \(5.11\)

  37. satellite73
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    \(30.75-27=3.25\) and \(3.25\div 5.11=.636\) approximately, so find the probability using a normal table that \(X<-.636\)

  38. yashar806
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    wait

  39. satellite73
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    that is my guess anyway, i would not bet any money on it

  40. yashar806
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    i have this formula

  41. yashar806
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    1 Attachment
  42. yashar806
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    i need to use that formula

  43. satellite73
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    i have no idea what p hat means

  44. yashar806
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    so for the n should I use 205?

  45. satellite73
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    yes that is \(n\) but i have no idea what p hat means, so i am useless at this point

  46. yashar806
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    thank you anyway

  47. yashar806
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    p hat actually equals to = x/n

  48. yashar806
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    I dont understand b first question also c

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

    sorry not my area

  50. yashar806
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    are u there?

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

    This is a problem where one can apply the binomial distribution. \[f(k) = \frac{n!}{k!(n-k)!} p^{k} (1-p)^{n-k}\] This is for when there are number of yes/no outcomes. If one yes has probability p for an individual outcome, this formula gives the probability of getting k yes outcomes out of n total outcomes. In this case p would be the probability of a single student being left handed. Now if k students are left handed, the proportion of left handed students is (let's call it y) \[y = k/n\] So what are the mean and variance of this? well to find the mean of the binomial distribution (the mean value of the number of students who are left handed) we'd do \[E[X] =\sum_k k f(k)\] But now we have some proportion k/n, but the probability is the same, f(k) \[E[X/n] =\sum_k \frac{k}{n} f(k) = \frac{1}{n}\sum_k k f(k) = \frac{1}{n}E[X] \]

  52. yashar806
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    actaully for the second one we have to use p hat

  53. yashar806
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    do you know p hat?

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

    \[\hat{p} = X/n\] Where X i the number of lefties and n is the total number of students in the class.

  55. yashar806
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    can you give me a number? i mean use b as an example?

  56. yashar806
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    cuz i dont really know how to find it ?

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

    p hat and X are not the usual kind numbers. They are labels to represent a number which has different probabilities for different values.

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

    For example X = k has the probability f(k) which I gave.

  59. yashar806
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    so you mean 27 / 205 ?

  60. yashar806
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    did you see question b ?

  61. yashar806
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    it asks for mean and standard deviation

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

    In statistics and probability theory, standard deviation (represented by the symbol sigma, σ) shows how much variation or "dispersion" exists from the average (mean), or expected value. A low standard deviation indicates that the data points tend to be very close to the mean; high standard deviation indicates that the data points are spread out over a large range of values. The standard deviation of a random variable, statistical population, data set, or probability distribution is the square root of its variance. It is algebraically simpler though practically less robust than the average absolute deviation.[1][2] A useful property of standard deviation is that, unlike variance, it is expressed in the same units as the data. Note, however, that for measurements with percentage as unit, the standard deviation will have percentage points as unit. In addition to expressing the variability of a population, standard deviation is commonly used to measure confidence in statistical conclusions. For example, the margin of error in polling data is determined by calculating the expected standard deviation in the results if the same poll were to be conducted multiple times. The reported margin of error is typically about twice the standard deviation ­– the radius of a 95 percent confidence interval. In science, researchers commonly report the standard deviation of experimental data, and only effects that fall far outside the range of standard deviation are considered statistically significant – normal random error or variation in the measurements is in this way distinguished from causal variation. Standard deviation is also important in finance, where the standard deviation on the rate of return on an investment is a measure of the volatility of the investment. When only a sample of data from a population is available, the population standard deviation can be estimated by a modified quantity called the sample standard deviation.

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

    No, I did not mean 27/205. By X I did not mean the number of seats for left handed people. I meant the number of left handed people. There are different probabilities for different numbers of left handed people.

  64. yashar806
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    can you solve it ? cuz i cant

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

    • Attachments:

Ask your own question

Ask a Question
Find more explanations on OpenStudy

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.