Confidence limits for Population Mean 总体均数的置信限 Parameter H=X± Error Statistic± Its error X-F=Error X Error X Error =20 Ⅹ±ZParameter = Statistic ±Its Error Confidence Limits for Population Mean 总体均数的置信限  = X  Error = Error =  − X X X X Z    = − = = Z  x  X Z X =  Error Error X − 