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发表于 7-3-2010 10:39 AM
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发表于 7-3-2010 11:06 AM
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回复 语曦
walrein_lim88 发表于 5-3-2010 04:33 PM
can you check again for your solution.for the multiple of 4,4&8(condition 3) ,i think it is a repeatation. |
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发表于 7-3-2010 11:35 AM
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本帖最后由 walrein_lim88 于 7-3-2010 11:37 AM 编辑
回复 162# 语曦
no la..for 1st part multiple 4 ..i nv include 8...tats y oni left 7 numbers(1-7)
不过你这题真的很麻烦。。哈哈。。。做到我好痛苦。。 |
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发表于 18-3-2010 01:13 PM
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请问15 ≤ x < 18 的class width是多少? |
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发表于 18-3-2010 01:26 PM
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回复 164# 海涵
应该是18-15=3,通常in the form of inequalities, a<x<b , a and b are the boundary ald..
so class width = b - a |
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发表于 18-3-2010 02:12 PM
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15≤x<18
18≤x<21
21≤x<27
27≤x<33
那么plot histogram的话,x-axis要怎样label? |
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发表于 18-3-2010 02:38 PM
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回复 166# 海涵
可以知道下他的FREQUENCY吗?? |
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发表于 18-3-2010 02:48 PM
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age,x frequency
15≤x<18 14
18≤x<21 38
21≤x<27 44
27≤x<33 16
33≤x<39 6
39≤x<45 2 |
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发表于 18-3-2010 02:56 PM
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不管是
a<x<b or a≤x≤b or a≤x<b or a<x≤b
只要是involving inequlities 的class width 都是 = b - a ?? |
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发表于 18-3-2010 02:58 PM
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发表于 18-3-2010 03:04 PM
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本帖最后由 walrein_lim88 于 18-3-2010 03:06 PM 编辑
age,x frequency
15≤x<18 14
18≤x<21 38
21≤x<27 44
27≤x<33 16
33≤x<39 6
39≤x<45 2
海涵 发表于 18-3-2010 02:48 PM
我这里PLOT不到。。所以大概写出来吧。。(用 2cm/1 box of graph = 3 class width)
0....15 (2cm) 18 (2cm) 21 (4cm) 27 (4cm) 33 (4cm) 39 (4cm) 45
Area of histrogram = frequency
Lets class width, 3 = 1 unit of frequency
Lets 2cm = 1 unit frequency
15-18 - 14 x 2cm
18-21 - 38 x 2cm
21-27 - 22 x 2cm
27-33 - 8 x 2cm
33-39 - 3 x 2cm
39-45 - 1 x 2cm |
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发表于 20-3-2010 12:59 PM
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帮忙解答。。。
age,x frequency
15≤x<18 14
18≤x<21 38
21≤x<27 44
27≤x<33 16
33≤x<39 6
39≤x<45 2
1)plot cumulative frequency curve 的话,x-axis 要怎么label??是(15+18)/2还是直接用15 18 21.。。
2)算median时,lower boundary 是多少?
3)算mean时,formula的x是不是直接用(15+18)/2 ??
age in years no.of teenagers
12- 4
13- 10
14- 27
15- 110
16- 212
17- 238
4)算median的话,lower boundary 是多少?? |
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发表于 20-3-2010 01:11 PM
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这题怎么做。。
the number of personal computers sold each week by a shop for a period of 25 weeks are as follows.
10 8 7 4 4 18 9 14 17 11 5 4 5
7 10 12 14 10 9 29 7 6 5 20 15
1)find the percentage of the weeks in which the number of personal computers sold each week is within one standard deviation from mean. |
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发表于 20-3-2010 01:23 PM
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发表于 21-3-2010 10:19 AM
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本帖最后由 whyyie 于 21-3-2010 10:22 AM 编辑
1. An article has 1500 words with 400 misprints. Find the probability that words 227 and 338 will contain no misprints.
2. Given accuracy of a test is 0.8. If a population of 500 people go through the test. Find the probability
-> at least 0.7 of people are tested correctly.
-> that 360 to 410 people are tested correctly. |
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发表于 21-3-2010 01:59 PM
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回复 175# whyyie
我不是很明白下第一题。
至于 第二题,可不可以提供下答案? |
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发表于 21-3-2010 03:10 PM
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回复 175# whyyie
用normal approximation with mean=np, variance = npq |
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发表于 21-3-2010 03:38 PM
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发表于 21-3-2010 03:38 PM
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发表于 21-3-2010 03:38 PM
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