Question 1 ) 點搵class interval?
question 2)
The following table shows the monthly fees for the airtime of mobile phones of 200 people. Complete the table.
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Monthly fee($) | Class mark($) | Frequency
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| 35.5 | 21
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| 65.5 | 64
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| 95.5 | 58
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| 125.5 | 42
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| 155.5 | 15
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how to find class interval?
2012-01-25 11:47 pm
回答 (2)
2012-01-27 5:44 pm
✔ 最佳答案
(1) Let L = Lower boundary of an interval.U = Upper boundary of an interval.
(L + U)/2 = Class Mark of the interval...........(1)
U - L = Width of each class = Class Mark of an interval - Class Mark of the previous interval .............(2)
(2)
From the chart provided, for the 1st class, we get
(L + U)/2 = 35.5
that is L + U = 71 ..............(1)
U - L = 65.5 - 35.5 = 30 ........(2)
(1) + (2) we get
2U = 71 + 30 = 101
so U = 50.5 and L = 71 - U = 71 - 50.5 = 20.5
That means the class boundary of the 1st interval is 20.5 to 50.5.
So Class interval is (20.5 + 0.5) to (50.5 - 0.5) = 21 to 50.
Next class is 51 to 80, 81 to 110, 111 to 140 and 141 to 170.
2012-01-26 2:40 am
442!!!!!!!
2012-01-25 18:41:21 補充：
n+n
2012-01-25 18:41:21 補充：
n+n
收錄日期: 2021-04-25 22:44:27
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https://hk.answers.yahoo.com/question/index?qid=20120125000051KK00282