&(-1.96)=0.025,即P(§<-1.96)=0.025由对称性可得P(§>1.96)=0.025所以P(|§|<1.96)=1-P(§<-1.96)-P(§>1.96)= 1-0.025-0.025 = 0.95选C
正态分布以Y轴为对称轴&(-1.96)=0.025,即P(§<-1.96)=0.025由对称性可得P(§>1.96)=0.025所以P(|§|<1.96)=1-P(§<-1.96)-P(§>1.96)= 1-0.025-0.025 = 0.95