KBaHTIUIb xp OnpeneJUleTCR KaK KOpeHb ypaBHeHIDI
\f
(m;
'Ax
p
)
="
.,
i
=p,
rne
\f(X;
J.1)
=
e-
Il
L
~,.
<l>YHKI.J.IDI
\f(X;
J.1)
Ta6YJIHpOBaHa
(CM.
i=x
I.
n.2.2).
COOTHoweHMR
MelKAY
pacnpeAeneHMRMM
1.
PacnpeneJIeHHe 3pJIaHra nopAAKa m onHCbIBaeT
pacnpene-
JIeHHe
C.JIY'IaHHoH
BeJIJilIHHbI X = XI + X
2
+ ... +
X""
npenCTaBJUI-
IOIUeH C060H
CYMMY
m
He3aBHCHMbIX
CJIyqaHHblX BeJIWlHH,
KaJK,lJ:lUI
H3
KOTOpbIX
pacnpeneJIeHa
no
nOKa3aTeJIbHOMY
3aKoHy pacnpeneJIe-
HIDI C
OnHHM
H
TeM
xe
napaMeTPoM
A.
B 60JIbllIHHCTBe
noc06HH
no
TeopHH BepoRTHocTeH
non
nOPAA-
KOM
pacnpeneJIeHIDI 3pJIaHra
nOHHMaeTCR
qHCJIO
m He3aBHCHMbIX
nOKa3aTeJIbHO pacnpeneJIeHHblX CJIaraeMblX, BXOMIUHX B
cYMMY
X = X I + X2 + ... + X",. OnHaKo B HeKoTophlX
noc06IDIX
nOPAAKoM
pacnpeneJIeHIDI Ha3bIBaIOT
qHCJIO,
KOTopoe Ha enHHHUY MeHbllIe
qHCJIa
CJIaraeMblX B
3TOH
cYMMe (CM., HanpHMep, [39]).
2.
lIpH
m = 1pacnpeneJIeHHe
3pJIaHfa
COBnanaeT C nOKa3aTeJIb-
HbIM pacnpeneJIeHHeM.
3. PacnpeneJIeHHe 3pJIaHra nopAAKa m
RBJUleTCH
qaCTHbIM CJIy-
qaeM raMMa-paCnpeneJIeHIDI, napaMeTPoM
<POPMbI
KOToporo
HBJUl-
eTCH
ueJIoe nOJIO)llliTeJIbHOe
qHCJIO
m
(a
= m).
Bce
xapaKTepHCTHKH
pacnpeneJIeHIDI
3pJIaHra
nopAAKa m onpeneJIRIOTCH
no
TeM
xe
<pOPMYJIaM,
qrO
H
COOTBeTCTByroIUHe
xapaKTepHCTHKH
raMMa-pac-
npeneJIeHIDI
(c
3aMeHOH
BO
Bcex
<POPMYJIax
a Ha m).
4. PacnpeneJIeHHe
3pJIaHra
TeCHO
CBR3aHO
C pacnpeneJIeHHeM
lIyaccoHa
(CM.
n.2.2).
5.
PacnpeneJIeHHe 3pJIaHra nOPAAKa m + 1 C napaMeTPOM
Mac-
llITa6a
1..=1 HHOfna Ha3bIBaIOT nOKa3amellbHo-cmeneHHblM
pacnpeiJelleHueM
C napaMeTPOM
<pOPMbI
m.
6.
PacnpeneJIeHHe
3pJIaHra
nopAAKa m HBlliIeTCH
HenpepblB-
HblM
aHaJIOrOM
0TPHuaTeJIbHOrO 6HHOMHaJIbHOrO pacnpeneJIe-
HIDI
1 C napaMeTPaMH m, p, KOTopoe OIIHCbIBaeT pacnpeneJIeHHe
CYMMbl
m He3aBHCHMhlX c.JIY'IaHHblX BeJIJilIHH,
KaJK,lJ:lUI
H3
KOTO-
pbIX HMeeT reOMeTPHqeCKOe pacnpeneJIeHHe 1 C
OnHHM
H
TeM
xe
napaMeTPoM
p.
O~eHMBaHMe
napaMeTpOB
"
(X")2)
_
(_1_)
A"
=
~"
(MM),
m---
"2'
"
-
s;
(V
x
)
X
rne
(a)
- ueJIoe
qHCJIO,
6mDlca1:1mee
K
a.
146
~Mcen
reHepMpOBaHMe
cny~aAHWX
1
Xi
=--In(r
1
·r
2
•
..
• .r",).
A
Ta6nM~b1
Moryr
6bITb HCnOJIb30BaHbl Ta6JIHUbI, npHMeHHeMble
npH
BbI-
qHCJIeHHHX,
cBH3aHHbIX C pacnpeneJIeHHeM
IlyaccoHa
(CM.
n.
2.2)
H
raMMa-pacnpeneJIeHHeM
(CM.
n.
3.10).
TeXHMKa
BbI~McneHMA
IlpH
BbIllOJIHeHHH BblqHCJIeHHH,
CBR3aHHbIX
C pacnpe.n:eJIeHHeM
3pJIaHfa,
nOMHMO
Ta6JIHU
HenOJIHOH
raMMa-<PYHKUHH
[7]
MOryr
6blTb HcnOJIb30BaHbI Ta6JIHUbI
<PYHKUHH
(CM.
n.2.2):
x
00
i
'l'(x;J.1)
=e-
Il
~
H
\f(x;
J.1)
=e-
Il
L
~I'
X.
;=x
I.
<l>YHKUHH
'l'(x;
J.1)
H
\f
(x;
J.1)
CBH3aHbI
C
llJIOTHOCTbIO
BepoHTHO-
CTH
f(x)
H
<PYHKUHeif
pacnpeneJIeHIDI
F(x)
3aKOHa
3pJIaHfa
nopAA-
Ka
m
oqeBMHbIMH
COOTHolIIeHHHMH:
f(x)
= A'l'(m
-1;
'Ax)
H
F(x)
=
\f
(m;
Ax)
(x
~
0).
3.11.2.
HOPMMPOBAHHOE PAcnPEAEIlEHME
3pnAHrA
m-ro
nOPSIAKA
= (Am)'"
Z",-Ie->.nu:
Z
~
0
f(z)
IInOTHOCTb
(m
-I)!
' '
BepOJITHOCTH
rne
A - napaMeTp
MacllITa6a
(A
> 0);
m - napaMeTP
<pOpMbl,
n 0p
Jl
0 0K
pac-
np
eo
ell eH
UJl,
ueJIoe
nOJIO)i(H.TeJIbHOe
qHCJIO
(m
~
1)
F(z)
=
1-
e-).ml
1:
(A~~)i
=
<l>YHKUHH
i-O
I.
pacnpeneJIeHIDI
=
e-).",l
~
(Amd
£..J
.,
i=m
I.
Xl(t)
=(~~",
XapaKTepHc~eCKaJl
Az-it)
<PYHKUIDI
_ 1
MaTeMaTJilIeCKOe
z=-
A
mKH,ZJ;aHHe
147