s p 2 = ( n − 1 ) S x 2 + ( m − 1 ) S y 2 m + n − 2 s_p^2=\frac{(n-1)S_x^2+(m-1)S_y^2}{m+n-2}
s
p
2
=
m+n−2
(n−1)S
x
+(m−1)S
y
匿名回答于2024-06-10 19:59:21