Statistics with Probability

You must be logged in to reply to this topic.

  • Author
    Posts
  • #12967

    Ezra Halleck
    Participant

    3. The distribution of grades on a quiz taken by 100 students is given in the table

    (a) Compute the mean and standard deviation of this distribution. [Use definition of standard deviation (weighted sum of deviations from mean square).]
    (b) Find mean & standard deviation of sample mean for random sample of size 16.

    #16169

    Sunny3oy
    Member

    Where is thy table? WHERE ART THOU!

    #16171

    Anonymous
    Inactive

    I was wondering the same about the table

    #16172

    Anonymous
    Inactive

    I was wondering the same about the table

    #16181

    Roger Herra
    Participant

    should a table be created??

    #16185

    Afzal
    Participant

    grade number
    1


    10
    2


    40
    3


    30
    4


    20

    …………………………………. this is the table/:

    #16189

    yuxiaolin
    Member

    i think we can get the table on excel file, isn’t it?

    #16195

    Ezra Halleck
    Participant

    Afzal is right. 10 students got a grade of 1, 40 a grade of 2, 30 a grade of 3 and 20 a grade of 4. The average grade will be between 2 and 3, but not necessarily 2.5. In fact 260 divided by 100 is 2.6.

    #16219

    Ziyuan Wu
    Member

    E(x)=1(.1)+2(.4)+3(.3)+4(.2)=2.6

    #16222

    (x-u)^2 1 2 3 4
    x

    P(x) 1/10 4/10 3/10 2/10

    #16240

    a) mean = 1+2+6+8/10 =2.6

    b) v[x]= e[x-u)^2 = 3.30

    c) sd[x]=.825

    #16272

    igorekk132
    Participant

    hmm for A i got
    mean = 2.6
    SD= 0.916

    #16276

    Ezra Halleck
    Participant

    x P(x) x*P(x) (x-mu)^2 (x-mu)^2*P(x)
    1 0.1 0.1 2.56 0.256
    2 0.4 0.8 0.36 0.144
    3 0.3 0.9 0.16 0.048
    4 0.2 0.8 1.96 0.392
    2.6 0.84 var
    0.916515139 sd

    Almost, SD is 0.917.

    #16277

    What is the variance 0.84?

    #16278

    did anyone do part b? does the mean remain the same ?

Viewing 15 posts - 1 through 15 (of 17 total)

You must be logged in to reply to this topic.