英文數學統計

👨🏻‍🏫 學術台數學

hooki

2013-10-05 9:58 pm

1.A marketing research company wants to study the spending on lunch for those who work in Central. A sample is obtained by convenience sampling method and the following is the result:

$65$35$48$50$46$38$38$43$68$80$55

(a)Compile the mean, variance and standard deviation.

(b)Prepare the stem-and-leaf display.

(c)Find the first quartile, the median, and the third quartile.

(d)Describe the shape of the distribution of the data. Explain your answer.

更新1:

求完整式+答案

更新2:

想問mean, variance and standard deviation如果用計算機計,ok?

更新3:

計算機計到麼?

更新4:

The shape of data follows normal distribution. Most of the data is within the range 35 - 70 為甚麼是35 - 70不是35 - 68?

回答 (2)

myisland8132

2013-10-05 11:48 pm

✔ 最佳答案

(a) The average is (65 + 35 + ... + 55)/11 = 51.4546

Variance = [(65 - 51.4546)^2 + ... + (55 - 51.4546)^2]/10 = 203.2727

Standard deviation = 14.2574

(b) Stem and Leaf Plot:

StemLeaf35 8 843 6 850 565 8780
(c) First quartile = (38 + 43)/2 = 40.5

Median = 48

Third quartile = (55 + 65)/2 = 60

(d) The shape of data follows normal distribution. Most of the data is within the range 35 - 70.

2013-10-07 00:13:47 補充：
1 我用Excel計算的﹐不過式子是這樣。
2 因為要等距。即第一部份0-35﹐第二部份35-70﹐第三部份70-105

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知足常樂

2013-10-07 8:41 am

myisland8132，應該未必係normal，我諗可能答 skew to the right 會安全一點。

因為唔係太 symmetric。

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