, , 1, 2, 3,... X. , X 1, X 2,...: Xk , X k - .
Mn (X) = (X 1 + X 2 +...+ Xn) / n
,
Dn (X) = ((X 1 - Mn (X))2 + (X 2 - Mn (X))2 +...+ (Xn - Mn (X))2) / (n 1)
X ( , X). .
a X, An - , ε , 0 < α < 1. 2 ε An α, , - ε ≤ An a < ε α. An, α , ] An ε, An + ε ] a, a, α , An [ a ε, a + ε [.
, X 1, X 2,..., Xn , X. (X 1 + X 2 +...+ Xn) / n N, (m, σ n -1/2), m X, σ . - ε ≤ N m < ε
(- ε) / (σ n -1/2) ≤ (N m) / (σ n -1/2) < ε / (σ n -1/2)
, ,
p (- ε ≤ N m < ε) = p (- ε / (σ n -1/2) ≤ (N m) / (σ n -1/2) < ε / (σ n -1/2)) = p ((N m) / (σ n -1/2) < ε / (σ n -1/2)) - p ((N m) / (σ n -1/2) < - ε / (σ n -1/2)).
(N m) / (σ n -1/2) (0, 1),
exp (- t 2 / 2) / (2 π)½,
|
|
- ∞ ε / (σ n -1/2), - - ∞ - ε / (σ n -1/2). ,
p (- ε ≤ N m < ε) = (2 π)-½ [ - s, s ] exp (- t 2 / 2) dt
s = ε / (σ n -1/2) = ε n 1/2 / σ.
erf (z) = 2 π-½ [ 0, z ] exp (- t 2) dt
(error function). ,
p (- ε ≤ (X 1 + X 2 +...+ Xn) / n m < ε) = erf (ε (n / 2)1/2 / σ).
. ,
p (- ε ≤ (X 1 + X 2 +...+ Xn) / n m < ε) = erf (ε (n / 2)1/2 / σ).