根据空气质量指数API的不同.可将空气质量分级如下表: 对某城市一年的空气质量进行监测.获得的API数据按照区间.....进行分组.得到频率分布直方图如图. (1)求直方图中的值, (2)计算一年中空气质量为良的天数, (3)某环保部门准备在一年内随机到该城市考察两次空气质量.求两次考察空气质量都为良的概率．题目和参考答案——青夏教育精英家教网—

题目内容

（本题12分）根据空气质量指数API（为整数）的不同，可将空气质量分级如下表：

对某城市一年（365天）的空气质量进行监测，获得的API数据按照区间，，，，，进行分组，得到频率分布直方图如图.

（1）求直方图中的值；

（2）计算一年中空气质量为良的天数；

（3）某环保部门准备在一年内随机到该城市考察两次空气质量，求两次考察空气质量都为良的概率（结果用分数表示）．

（1） …… 4分

（2）146天； …… 8分

（3） …… 12分

解析:

略

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