Re: [理工] probability

[DIDIMIN ( )]

※ 引述《KAINTS (RUKAWA)》之銘言：
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: 沒什麼想法QQ

The CDF of random variable is

                      a x
F(w) = Pr(W<w) = 2 * ∫∫  1/a^2 dydx = 1 - 1/w, w>1
                      0 x/w

Thus, the PDF of random variable is

f(w) = 1/w^2, w>1


Hint:
        Y        W=Y/X    X=Y
        ↑      ∕      ／
       a│──────┐
        │    ∕ @@ ／│   . W=X/Y
        │   ∕   ／  │.
        │  ∕  ／ ##.│
        │ ∕ ／  .   │
        │∕／ .      │
        │／.         │
        └───────→X
       0              a

The CDF is the probability of sum of @@ and ## areas.

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