题干

在某项针对18~35岁的青年人每天发微博数量的调查中,设一个人的“日均发微博条数”为m,规定:当m≥10时为A级,当5≤m<10时为B级,当0≤m<5时为C级.现随机抽取30个符合年龄条件的青年人开展每人“日均发微博条数”的调查,所抽青年人的“日均发微博条数”的数据如下:

11    10    6     15    9    16   13   12   0    8

2     8     10    17    6    13   7    5    7    3

12    10    7     11    3     6   8    14   15   12

(1)求样本数据中为A级的频率;

(2)试估计1000个18~35岁的青年人中“日均发微博条数”为A级的人数.

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答案(点此获取答案解析)

解:(1)m≥10的人数有15人,
则频率=1530
=
1
2
(2)1000×

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    This study shows that while using the dishwasher might be easier, the old-fashioned method of cleaning up could be better for your health.