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Slika - Shrani.si

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A. Juriˇ<strong>si</strong>ć in V. Batagelj: Verjetnostni račun in statistika 199<br />

✬<br />

Za vajo izračunajmo obe robni verjetnostni gostoti. Očitno velja:<br />

F (x, y) = 0 za (x, y) < (0, 0) in F (x, y) = 1 za (x, y) > (60, 60).<br />

Sedaj pa za (0, 0) ≤ (x, y) ≤ (60, 60) velja<br />

y x<br />

<br />

1<br />

F (x, y) =<br />

3600<br />

in<br />

✫<br />

pX(x) = F ′ X(x) =<br />

pY (y) = F ′ Y (y) =<br />

0<br />

60<br />

0<br />

60<br />

0<br />

0<br />

<br />

1<br />

dy =<br />

3600<br />

1<br />

60<br />

<br />

1<br />

dx =<br />

3600<br />

1<br />

60<br />

dydx = xy<br />

3600 .<br />

za 0 ≤ y ≤ 60,<br />

za 0 ≤ x ≤ 60,<br />

za vse ostale x in y pa je pX(x) = 0 ter pY (x) = 0, torej sta X in Y obe<br />

enakomerno porazdeljeni slučajni spremenljivki na intervalu [0, 60].<br />

Univerza v Ljubljani ▲<br />

❙ ▲<br />

▲<br />

● ❙ ▲<br />

▲<br />

☛ ✖<br />

▲<br />

✩<br />

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