2.从一批零件中抽出50个测量长度,得数据如下(单位:-|||-mm):-|||-19.88 20.1219.94 19.99 19.97 19.85 19.96-|||-20.23 19.8620.20 20.2020.10 19.6420.08-|||-19.98 19.8719.86 20.0020.11 19.7119.95-|||-20.02 19.9920.40 19.6219.99 19.9620.00-|||-20.03 20.0220.19 19.9320.18 20.0920.01-|||-19.70 20.0120.04 19.8720.05 20.0720.17-|||-19.90 19.6320.28 20.0820.52 19.4420.15-|||-20.02-|||-(1)试用简化计算公式求这组数据的均值和方差;-|||-(2)列出频数分布表;-|||-(3)作出频数直方图-|||-会国由加歌曲大把寒由,由10位评委为歌手打分,打分