单项选择题
A.0.5661B.0.5663C.0.5665D.0.5667E.0.5669
A.30σ2B.34σ2C.36σ2D.38σ2E.40σ2
A.δ4tx ,50σ2B.δ4tx ,60σ2C.δ4tx ,70σ2D.δ4tx ,80σ2E.δ4tx ,90σ2