问题
选择题
一次数学测试后，随机抽取九年级二班5名学生的成绩如下：78，85，91，98，98．关于这组数据的错误说法是（ ）
A．极差是20
B．众数是98
C．中位数是91
D．平均数是91
答案
根据定义可得，极差是20，众数是98，中位数是91，平均数是90．故D错误．
故选D．
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一次数学测试后，随机抽取九年级二班5名学生的成绩如下：78，85，91，98，98．关于这组数据的错误说法是（ ）
A．极差是20
B．众数是98
C．中位数是91
D．平均数是91
根据定义可得，极差是20，众数是98，中位数是91，平均数是90．故D错误．
故选D．
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