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March 27, 2017

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Consider the probability function. (Give your answers exactly.)

P(x) =
5 − x
10
, for x = 1, 2, 3, 4

(a) Find the mean.
Incorrect: Your answer is incorrect. (my answer was 1).

(b) Find the standard deviation.
(my answer was 1 also on this one. Please help, I just cant get the standard deviation.

  • Math question and answer check - ,

    You can p(x )
    because x values are given

    p( x ) = 5-x

    p(x) = 5-1 = 4
    p(x) = 5-2 = 3
    p(x) = 5-3 = 2
    P(x) = 5-4 = 1

    What about that 10 belong to

  • Math question and answer check - ,

    Ok, question is this the way to work this 5-4/10, 5-3/10, 5-2/10, 5-1/10 or do you divide by 4.

  • Math question and answer check - ,

    (5-x)/10
    (5-1)/10 = 0.4
    (5-2)/10 = 0.3
    (5-3)/10 = 0.2
    (5-4)/10 = 0.1

    x 1 2 3 4
    P(x) 0.4 0.3 0.2 0.1

    It is unclear. What is the 10 doing there

  • Math question and answer check - ,

    When you add up all the x's the total is 10 and it is over 10 that is how I came up with the mean of one the first time.

  • Math question and answer check - ,

    You can check question first
    P(x) = (5-x)/10 or 5-x/10

    it is easy to compute mean when you get p(x).

  • Math question and answer check - ,

    5-1/10= 4/10=.4
    I do appreciate the patience that you have with me. Am I getting close to it???

  • Math question and answer check - ,

    mean = 1(.4) + 2 (.3) + 3(.2) + 4(.1)
    Mean = .4 +.6 + .6 +.4
    Mean = 2.0

    variance = 1^2 (.4) 2^2(.3) + 3^2(.2) + 4^2(.1)
    variance = .4 + 1.2 + 1.8 + 1.6
    variance = 5

    Standard deviation = sqrt(variance - mean^2)
    Sqrt(5-2^2)) = 1

  • Math question and answer check - ,

    Thank you, once I see it worked out I can do others, just done one and got the mean correct so far.

  • Math question and answer check - ,

    variance = 1^2 (.4) + 2^2(.3) + 3^2(.2) + 4^2(.1

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