hooki 發問時間： 科學數學 · 7 年前

# 英文數學統計

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.

2 個已更新項目:

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

### 2 個解答

• 7 年前
最佳解答

(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

• 7 年前

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。