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用样本估计总体是中考命题的热点.现以2015年中考试题为例,对用样本估计总体的常见题型进行归纳如下,供你学习时参考.一、用样本的统计量估计总体的统计量例1(2015年绍兴卷)为了解某种电动汽车的性能,对这种电动汽车进行了抽检,将一次充电后行驶的里程数分为A,B,C,D四个等级,其中相应等级的里程依次为200千米,210千米,220千米,230千米,获得如下不完整的统计图(图1).根据以上信息,解答下列问题:(1)这次被抽检的电动汽车共有几辆?并补全条形统计图;
Using sample estimates overall is a hot topic in the senior high school entrance examination questions. Now take the 2015 mid-term exam questions as an example, the common problems with sample estimation generalized as follows, for your reference when learning. First, with the sample statistics to estimate the overall statistics Example 1 (Shaoxing, 2015) In order to understand the performance of a certain type of electric vehicle, the electric vehicle was sampled and tested. The mileage after a charge was divided into four levels of A, B, C and D, of which the corresponding level Of the mileage of 200 km, 210 km, 220 km, 230 km, get the following incomplete chart (Figure 1). Based on the above information, answer the following questions: (1) The electric car was sampled this time How many cars? And make up the bar chart;