Quiz 1
2003.10.23
1. (20%)
A magazine surveyed a sample of its subscribers every year. Some of the
responses from the survey are shown below.
Year
Percent Female
Average Age
Average Income
1996
5.8
35.2
40
1997
8.6
35.8
42
1998
7.3
33.9
41
1999
9.2
35.3
43
2000
9.8
36.6
46
(a) How many elements are in the data set? Write down these elements. (4%)
(b) How many variables are in the data set? Write down these variables. (4%)
(c) How many observations are in the data set? Write down these observations.
(4%)
(d) Which of the above variables are qualitative and which are quantitative?
(4%)
(e) Are the data time series or cross-sectional? (4%)
2. (40%)
Below you are given the examination scores of 20 students.
52
99
92
86
84
63
72
76
95
88
92
58
65
79
80
90
75
74
56
99
Let the first class be 50-59.
(a)Develop a frequency distribution, percent frequency distribution and a
relative frequency distribution. (10%)
(b) Develop a cumulative frequency distribution, cumulative percent frequency
distribution and a cumulative relative frequency distribution. (10%)
(c) Develop histogram and ogive. (10%)
(d) Based on the frequency table obtained in (a), compute the mean and variance
for the grouped data. (10%)
3. (40%)
The amount of time (in minutes) that a sample of students spends watching
television per day is given below.
2
1
0
2
0
2
1
2
0
2
1
2
(a) Compute the mean (4%)
1
(b) The standard deviation. (4%)
(c) The coefficient of variation. (4%)
(d) The 30th percentile. (4%)
(e) The median. (4%)
(f) The mode. (4%)
(g) The interquartile range. (4%)
(h) Provide a five-number summary for the data. (4%)
(i) Show the box plot. (4%)
(j) Determine the outliers. (4%)
4. (20%)
(a) Consider a sample with data values of 10, 20, 12, 17 and 16. Compute the
z-score for each of the five observations. (10%)
(b) The following observations are given for two variables
X
2
12
3
6
11
19
18
9
Y
5
8
18
20
22
30
10
7
Compute and interpret the sample correlation coefficient. (10%)
2