科目:初中數(shù)學 來源: 題型:閱讀理解
時間(分) | 15 | 20 | 25 | 30 | 35 | 40 | 45 | 50 | 55 | 60 |
人 數(shù) | 8 | 12 | 7 | 5 | 4 | 3 | 4 | 2 | 3 | 2 |
分組 | 頻數(shù) |
14.5-24.5 | 20 |
24.5-34.5 | m |
34.5-44.5 | n |
44.5-54.5 | 6 |
54.5-64.5 | 5 |
合計 | 50 |
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科目:初中數(shù)學 來源: 題型:
1 |
3 |
1 |
2 |
5 |
4 |
5 |
4 |
5 |
4 |
1 |
3 |
1 |
2 |
1 |
3 |
1 |
2 |
1 |
3 |
1 |
2 |
5 |
4 |
1 |
3 |
1 |
2 |
5 |
4 |
1 |
3 |
1 |
2 |
1 |
3 |
1 |
2 |
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科目:初中數(shù)學 來源: 題型:044
某年級300名同學的體重如下(單位:kg):
49, |
48, |
43, |
52, |
62, |
74, |
43, |
51, |
46, |
47, |
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51, |
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(1)請用計算器或計算機計算總體的平均數(shù)、方差和標準差(精確到0.01),并繪制總體的頻數(shù)分布直方圖;
(2)請用簡單隨機抽樣方法,從上述調(diào)查的數(shù)據(jù)中分別抽取樣本容量為10的兩個樣本,并分別計算這兩個樣本的平均數(shù)、方差和標準差,分別繪制這兩個樣本的頻數(shù)分布直方圖,結果一致嗎?如果分別抽取樣本容量為20、50的兩個樣本呢?
(3)通過以上的抽樣和計算,你有什么發(fā)現(xiàn)?并與同伴交流.
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