題目列表(包括答案和解析)
某年級300名同學(xué)的體重如下(單位: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)請用計算器或計算機(jī)計算總體的平均數(shù)、方差和標(biāo)準(zhǔn)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(jī)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(biāo)準(zhǔn)差,分別繪制這兩個樣本的頻數(shù)分布直方圖,結(jié)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.
下面是某校初中三年級一班60名同學(xué)心臟每分跳動次數(shù)的數(shù)據(jù):
72 |
70 |
66 |
74 |
81 |
70 |
74 |
53 |
57 |
62 |
58 |
92 |
74 |
67 |
62 |
91 |
73 |
68 |
65 |
80 |
78 |
67 |
75 |
80 |
84 |
61 |
72 |
72 |
69 |
70 |
76 |
74 |
65 |
84 |
79 |
80 |
76 |
72 |
68 |
65 |
82 |
79 |
71 |
86 |
77 |
69 |
72 |
56 |
70 |
62 |
76 |
56 |
86 |
63 |
73 |
70 |
75 |
73 |
89 |
64 |
(1)通常認(rèn)為初三學(xué)生(年齡在15歲左右)心臟每分跳動用60~69次為最好.請求出在上面60個數(shù)據(jù)中,不少于60,且又不大于69的數(shù)據(jù)共計出現(xiàn)的頻數(shù)與它們出現(xiàn)的頻率.
(2)在這個班級中有兩名長跑運動員,由于堅持體育鍛煉,心臟的收縮力強(qiáng),每分心跳次數(shù)僅為58次和56次.如果這兩名同學(xué)和每分心跳次數(shù)在60~69次的同學(xué)都看作是心臟非常好的,那么,心臟非常好的同學(xué)占全班同學(xué)的百分之多少呢?
將一張長方形紙片如圖所示折疊后,再展開,如果∠1=56°,那么∠2等于( ).
A.56° B.68° C.62° D.66°
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