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Miklós Schweitzer
1986 Miklós Schweitzer
10
Miklós Schweitzer 1986, Problem 10
Miklós Schweitzer 1986, Problem 10
Source:
September 12, 2016
Miklos Schweitzer
college contests
probability
random variables
Problem Statement
Let
X
1
,
X
2
X_1, X_2
X
1
,
X
2
be independent, identically distributed random variables such that
X
i
≥
0
X_i\geq 0
X
i
≥
0
for all
i
i
i
. Let
E
X
i
=
m
\mathrm EX_i=m
E
X
i
=
m
,
V
a
r
(
X
i
)
=
σ
2
<
∞
\mathrm{Var} (X_i)=\sigma ^2<\infty
Var
(
X
i
)
=
σ
2
<
∞
. Show that, for all
0
<
α
≤
1
0<\alpha\leq 1
0
<
α
≤
1
lim
n
→
∞
n
V
a
r
(
[
X
1
+
…
+
X
n
n
]
α
)
=
α
2
σ
2
m
2
(
1
−
α
)
\lim_{n\to\infty} n\,\mathrm{Var} \left( \left[ \frac{X_1+\ldots +X_n}{n}\right] ^\alpha\right)=\frac{\alpha ^ 2 \sigma ^ 2}{m^{2(1-\alpha)}}
n
→
∞
lim
n
Var
(
[
n
X
1
+
…
+
X
n
]
α
)
=
m
2
(
1
−
α
)
α
2
σ
2
[Gy. Michaletzki]
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