简单随机抽样,p=240/400=60%=0.6
方差=p*(1-p)*(1-f)/n=0.6*0.4*(1-400/N)/400=0.0006
标准差=0.024
95%置信区间为【0.6-1.96*0.024,0.6+1.96*0.024】=[0.552,0.647]=[55.2%,64.7%]
简单随机抽样,p=240/400=60%=0.6
方差=p*(1-p)*(1-f)/n=0.6*0.4*(1-400/N)/400=0.0006
标准差=0.024
95%置信区间为【0.6-1.96*0.024,0.6+1.96*0.024】=[0.552,0.647]=[55.2%,64.7%]