网址:http://m.1010jiajiao.com/timu_id_732927[举报]
在300个数据中,用随机抽样的方法抽取50个数据,在频率分布表中,52.5~55.5这一组的频率是0.3,那么估计总体数据落在52.5~55.5之间的约有
- A.90个
- B.60个
- C.50个
- D.15个
在300个数据中,用随机抽样的方法抽取50个数据,在频率分布表中,52.5~55.5这一组的频率是0.3,那么估计总体数据落在52.5~55.5之间的约有
[ ]
某年级300名同学的体重如下(单位:kg):
49, |
48, |
43, |
52, |
62, |
74, |
43, |
51, |
46, |
47, |
51, |
45, |
50, |
46, |
52, |
54, |
50, |
58, |
55, |
58, |
48, |
48, |
53, |
49, |
56, |
55, |
56, |
43, |
54, |
68, |
47, |
61, |
51, |
44, |
41, |
49, |
53, |
52, |
49, |
52, |
62, |
58, |
52, |
54, |
50, |
47, |
66, |
46, |
47, |
44, |
72, |
55, |
43, |
60, |
51, |
41, |
48, |
49, |
43, |
52, |
63, |
44, |
41, |
47, |
48, |
49, |
55, |
53, |
58, |
50, |
50, |
43, |
60, |
61, |
52, |
50, |
42, |
44, |
46, |
67, |
47, |
66, |
46, |
47, |
69, |
48, |
43, |
50, |
50, |
43, |
46, |
47, |
44, |
42, |
55, |
56, |
55, |
56, |
43, |
54, |
49, |
56, |
55, |
56, |
65, |
43, |
60, |
51, |
41, |
48, |
43, |
52, |
62, |
46, |
52, |
54, |
50, |
58, |
58, |
52, |
49, |
48, |
43, |
50, |
50, |
47, |
44, |
42, |
55, |
63, |
60, |
48, |
43, |
50, |
50, |
43, |
49, |
53, |
52, |
49, |
48, |
43, |
50, |
50, |
47, |
44, |
49, |
48, |
43, |
44, |
42, |
55, |
43, |
42, |
64, |
46, |
47, |
48, |
43, |
50, |
44, |
41, |
47, |
48, |
49, |
55, |
53, |
58, |
55, |
73, |
60, |
51, |
41, |
53, |
49, |
56, |
55, |
56, |
43, |
54, |
44, |
41, |
47, |
48, |
49, |
55, |
41, |
48, |
43, |
42, |
44, |
46, |
47, |
42, |
55, |
43, |
60, |
68, |
43, |
50, |
48, |
43, |
52, |
62, |
43, |
51, |
46, |
47, |
51, |
45, |
49, |
46, |
72, |
54, |
50, |
58, |
47, |
61, |
51, |
44, |
41, |
44, |
41, |
49, |
73, |
52, |
49, |
52, |
49, |
56, |
55, |
56, |
43, |
54, |
48, |
47, |
61, |
50, |
50, |
43, |
46, |
47, |
44, |
42, |
48, |
43, |
52, |
62, |
55, |
41, |
48, |
43, |
42, |
44, |
46, |
47, |
43, |
46, |
67, |
44, |
42, |
44, |
41, |
47, |
48, |
49, |
55, |
53, |
72, |
54, |
50, |
58, |
55, |
58, |
49, |
48, |
43, |
52, |
53, |
54, |
48, |
47, |
61, |
51, |
44, |
4l, |
49, |
53, |
72, |
49, |
52, |
47, |
66, |
46, |
47, |
49, |
48, |
43, |
50, |
49. |
(1)请用计算器或计算机计算总体的平均数、方差和标准差(精确到0.01),并绘制总体的频数分布直方图;
(2)请用简单随机抽样方法,从上述调查的数据中分别抽取样本容量为10的两个样本,并分别计算这两个样本的平均数、方差和标准差,分别绘制这两个样本的频数分布直方图,结果一致吗?如果分别抽取样本容量为20、50的两个样本呢?
(3)通过以上的抽样和计算,你有什么发现?并与同伴交流.
查看习题详情和答案>>(1)填写表中未完成的部分;
(2)画出频数分布直方图及频数折线图.
分组 | 频数 | 频率 |
3.95~4.25 | 2 | 0.04 |
4.25~4.55 | 6 | 0.12 |
4.55~4.85 | 25 | |
4.85~5.15 | ||
5.15~5.45 | 1 | 0.02 |
合计 | 1 |
为了了解某中学九年级300名学生的视力情况,从中抽测了一部分学生的视力,数据整理如下:
(1)填写表中未完成的部分;
(2)画出频数分布直方图及频数折线图.
分组 | 频数 | 频率 |
3.95~4.25 | 2 | 0.04 |
4.25~4.55 | 6 | 0.12 |
4.55~4.85 | 25 | |
4.85~5.15 | ||
5.15~5.45 | 1 | 0.02 |
合计 | 1 |