1 3 2 3 1 1. 2. N p N �1] N � p N (1) 3. 1.1 1.2 1.3 N � p N 1.3 1.4 � (28) ] 1.1 x n i x xi x x = 1 n n X i=1 xi (2) 1 1 x x s2 = 1 n n X i=1 (xi ;x)2 (3) s x x s s = v u u t1 n n X i=1 (xi ;x)2 (4) 1 2010-10-15 1 1.2 n xi y y = n X i=1 xi = x1 + x2 + ��� + xN = nx (5) y y xi �xi �y2 = � @y @x1 �2 �x2 1 + � @y @x2 �2 �x2 2 + ��� + � @y @xn �2 �x2 n = 1 �s2 + 1 �s2 + 1 ��� �s2 = ns2 y s2 y �y2 y s