A.R/C4 B.R/d2 C.s/c4 D.s/d2
A.μ>0,σ>0 B.μ>0,-∞<σ<+∞ C.-∞<μ<+∞,-∞<σ<+∞ D.-∞<μ<+∞,σ>0
A.973% B.2700ppm C.63ppm D.0027