填空题
从一班级中任取l0名学生做英语口语测试，成绩如下（单位：分）（平均数精确到个位）
76，90，84，86，81，87，86，82，85，83，
则样本平均数等于（）；样本方差等于（）.
说明：计算结果时可以使用计算器．
【参考答案】
84；13．2
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