题目

Parents are probably the closest people in the world to us. However, parent-child relationships are not always easy to deal with. What's worse, now that we live in an information age, the internet is bringing new challenges to family relations.The China Youth Children Research Center did a survey about such relationships in the United States, Japan, South Korea and China. According to the survey, the use of the Internet has become one of the main reasons for fights between parents and children in China and South Korea. “This shows that some parents consider the internet being a toy instead o当一组数据的平均数不是整数时，可用四舍五入的方法求得，然后分别用公式 ①S2=.计算这组数据的方差，则下列说法正确的是（　） A．用公式①求出的结果误差大　　    B．用公式②求出的结果误差大 C．用公式①和公式②求出的结果误差一样大 D．以上都有可能