+ Reply to Thread
Page 1 of 2 1 2 LastLast
Results 1 to 15 of 19

Thread: Stats Problem

  1. #1
    Points: 236, Level: 4
    Level completed: 72%, Points required for next Level: 14

    Posts
    12
    Thanks
    0
    Thanked 0 Times in 0 Posts

    Stats Problem



    On average, there are three misprints in every 10 pages of a particular book. If every chappter of the book contains 35 pages, what is the probability that chapters 1 and 5 have 10 misprints?
    Just would like to know if I am right or not. If not could you point me in the right direction?

    I think this is the answer to solve it by binomial distribution and here what I got
    N being total pages and P being percent of occurrences ( 3/10 = .3 )
    n = 35 p = .3

    Probability of 10 occurrences being 0.1454

  2. #2
    Points: 236, Level: 4
    Level completed: 72%, Points required for next Level: 14

    Posts
    12
    Thanks
    0
    Thanked 0 Times in 0 Posts

    Re: Stats Problem

    Normal distribution just those two types of distribution. I thought binomial because the distribution is yes/no there either is mistake or their isn't one. Should I have used normal distribution but that doesn't seem to be the case to me am I wrong?

  3. #3
    Points: 236, Level: 4
    Level completed: 72%, Points required for next Level: 14

    Posts
    12
    Thanks
    0
    Thanked 0 Times in 0 Posts

    Re: Stats Problem

    Yes but not recently we did at the start of the semester, have not really used it since then.

  4. #4
    Points: 236, Level: 4
    Level completed: 72%, Points required for next Level: 14

    Posts
    12
    Thanks
    0
    Thanked 0 Times in 0 Posts

    Re: Stats Problem

    I will try just trying to recall how to find λ

  5. #5
    Points: 191, Level: 3
    Level completed: 82%, Points required for next Level: 9

    Posts
    7
    Thanks
    0
    Thanked 0 Times in 0 Posts

    Re: Stats Problem

    The distribution is Poisson as the probability of occurance of success (i.e. the misprints) is too low as compared to the total number of cases (only 3 misprints out of 10 pages). here lamda=4.28 [(3*10*5)/35],x=10...hence on counting you will get the answer...

  6. #6
    Points: 191, Level: 3
    Level completed: 82%, Points required for next Level: 9

    Posts
    7
    Thanks
    0
    Thanked 0 Times in 0 Posts

    Re: Stats Problem

    @halfnormal....didnt get u....can u plz explain more?

  7. #7
    Points: 236, Level: 4
    Level completed: 72%, Points required for next Level: 14

    Posts
    12
    Thanks
    0
    Thanked 0 Times in 0 Posts

    Re: Stats Problem

    If lambda 18.3428571 and x = 10 (being the occurances) then 0.0128 is the answer I got
    Equation being f(x, lambda) = [(lambda^x)(e^lambda)]/ x! using tablet calculator got me 0.0128 with the lamba of 4.28[(3*10*5)/35]
    Last edited by gijin; 05-03-2012 at 01:09 AM.

  8. #8
    Points: 191, Level: 3
    Level completed: 82%, Points required for next Level: 9

    Posts
    7
    Thanks
    0
    Thanked 0 Times in 0 Posts

    Re: Stats Problem

    the answer would be 0.007

  9. #9
    Points: 236, Level: 4
    Level completed: 72%, Points required for next Level: 14

    Posts
    12
    Thanks
    0
    Thanked 0 Times in 0 Posts

    Re: Stats Problem

    Doesn't that seem a little low considering if there 3 mistakes every 10 pages and you have 35 pages you'd almost think there would be between 9,10,11 . I think a higher percent then .7%

  10. #10
    Points: 191, Level: 3
    Level completed: 82%, Points required for next Level: 9

    Posts
    7
    Thanks
    0
    Thanked 0 Times in 0 Posts

    Re: Stats Problem

    sorry i did a small mistake. 3 misprints per 10 pages = 3/10 misprints per page. now one chapter has 35 pages means (3*35)/10 misprints. now there are 5 chapters....so total misprints= (3*35*5)/10 misprints = 52.5. this 52.5 is the lamda i think.

  11. #11
    Points: 236, Level: 4
    Level completed: 72%, Points required for next Level: 14

    Posts
    12
    Thanks
    0
    Thanked 0 Times in 0 Posts

    Re: Stats Problem

    So if λ is ( .3 * 35 ) you get 10.5 plug that with Prob being exactly 10 you get .1236 Poisson Distribution and Cumulative Poisson Distribution of .521 . Don't think the cumulative one matters but just incase

  12. #12
    Points: 236, Level: 4
    Level completed: 72%, Points required for next Level: 14

    Posts
    12
    Thanks
    0
    Thanked 0 Times in 0 Posts

    Re: Stats Problem

    So my last one was wrong too. Could you give me another hint?

  13. #13
    Points: 191, Level: 3
    Level completed: 82%, Points required for next Level: 9

    Posts
    7
    Thanks
    0
    Thanked 0 Times in 0 Posts

    Re: Stats Problem

    @halfnormal...we need to include 5 in calculating lamda as the total number of misprints for chapters 1 to 5 is required...

  14. #14
    Points: 191, Level: 3
    Level completed: 82%, Points required for next Level: 9

    Posts
    7
    Thanks
    0
    Thanked 0 Times in 0 Posts

    Re: Stats Problem

    oops.....ok,we will multiply with 2 and not 5....now i think we will get the answer...

  15. #15
    Points: 236, Level: 4
    Level completed: 72%, Points required for next Level: 14

    Posts
    12
    Thanks
    0
    Thanked 0 Times in 0 Posts

    Re: Stats Problem


    Oh ( .3 * 2(35) ) would get 21 as lambda since two chapters of 35 pages is 70

+ Reply to Thread
Page 1 of 2 1 2 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts








Advertise on Talk Stats