Download Quiz 1 (2002)

Quiz 1
91.10.22
1. (20%)
A magazine surveyed a sample of its subscribers. Some of the responses from the
survey are shown below.
Subscribers
Sex
Age
Income ($1000)
A
F
22
45
B
M
21
53
C
F
33
82
D
M
38
30
(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. (20%)
(a) Construct a stem-and-leaf display for the following data. (10%)
11.3
9.6
10.4
7.5
8.3
10.5
10.0
9.3
8.1
7.7
7.5
8.4
6.3
8.8
(b) A student has completed 20 courses in the School of Arts and Sciences. His
grades in the 20 courses are shown below.
A
B
A
B
C
C
C
B
B
B
B
A
B
B
B
C
B
C
B
A
Develop a frequency distribution and a relative frequency distribution. (10%)
3. (60%)
The amount of time (in minutes) that a sample of students spends watching
television per day is given below.
40
28
71
48
49
(a) Compute the mean (4%)
(b) The standard deviation. (4%)
1
35
40
57
(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%)
(k) Construct a frequency distribution, a cumulative frequency distribution and
a relative frequency distribution. Let the first class be 10-19. (10%)
(l) Based on the frequency table obtained in (k), compute the mean and variance
for the grouped data. Compare with the results in (a) and (b). (10%)
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) A department of transportation’s study on driving speed and mileage for
midsize automobiles resulted in the following data.
Driving
30
50
40
55
30
25
60
25
50
55
Speed
Millege
28
25
25
23
30
32
21
35
Compute and interpret the sample correlation coefficient. (10%)
2
26
25