? 發問於 科學及數學數學 · 1 十年 前

Normal Distribution 題目

2.Consider a standard normal variable Z. Find c such that

a)P(Z < c) = 0.8

b)P(Z < c) = 0.27

c)P(0 < Z < c) = 0.311

點做

更新:

find 0.8 from the table and c = 0.8416

我唔知點樣睇個table

更新 2:

find 0.8 from the table and c = 0.8416

我唔知點樣睇個table

0.8416係起1.0 個行

更新 3:

this is answer

2.a) 0.84b) –0.61c) 0.88

比個process我 thx

2 個解答

評分
  • Marie
    Lv 6
    1 十年 前
    最佳解答

    2.

    the left hand side column and top row of the normal distribution table is the Z value

    the value inside the table represent the probability

    a)

    since P(Z < c) is more than 0.5

    it should be consider the inverse part

    P(Z < c) = 0.8

    1 - P(Z > c) = 0.8

    P(Z > c) = 0.2

    c = 0.84

    find the probability about 0.2 from the table, the Z value of this probability is 0.84

    b)

    P(Z < c) = 0.27

    c = -0.61

    find the probability about 0.27 from the table, the Z value of this probability is 0.61

    since P(Z < c) is less than 0.5, the Z value is negative

    c)

    P(0 < Z < c) = 0.311

    0.5 - P(Z > c) = 0.311

    P(Z > c) = 0.189

    c = 0.88

  • 1 十年 前

    look at the inverse normal function table,

    a)inverse of [Q] (p) = z

    find 0.8 from the table and c = 0.8416

    b)invese of p(0.27) = -p(0.73) c = -0.6128

    i am not sure about the third one, should be something like 0.5 - -p(0.689)

    =0.5 - 0.4930

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