ID 1050 Practice Exam 3
Your name (print)________________________
Discrete Data
The set of questions below all use the following set of data points taken from a discrete sample:
1, 2, 3, 4, 4, 4, 5, 5, 6, 6.
1) Make a bar graph of this data using the blank graph provided.
2) What is the mean of this distribution?
a) 10
b) 4
c) 4.5
d) 9
5) What is the standard deviation of this sample
data set?
a) 1.63
b) 1.55
c) 4.00
d) 2.67
3) What is the median of this distribution?
a) 10
b) 4
c) 4.5
d) 9
6) What is the variance of this distribution?
a) 1.63
b) 1.55
c) 4.00
d) 2.67
4) What is the mode of this distribution?
a) 10
b) 4
c) 4.5
d) 9
7) What is the skewness of this distribution?
a) 1.22
b) 4.00
c) 1.41
d) 0.00
Definitions
8) A set of classes or groups based on name only,
without a mathematical value or order (example:
hair color):
a) A nominal scale
b) An ordinal scale
c) An interval scale
10) A set of classes or groups based on their
mathematical value relative to an absolute zero
(example: height):
a) A nominal scale
b) An ordinal scale
c) A ratio scale
9) A set of classes or groups based on relative rank
only, without a mathematical value (example:
relative dominance):
a) A nominal scale
b) An ordinal scale
c) A ratio scale
11) The entire set of people or objects one wishes to
characterize is called the _______. The subset
that is actually measured is called the ________.
a) Population; sample
b) Sample; population
R. Gist
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Ver. D, Rev. 1
ID105 Exam 3
Continuous Data
The set of questions below are all taken from the following set of data which comes from a
sample which is continuously distributed:
1.1, 1.2, 1.3, 1.8, 2.4, 2.5, 3.7, 4.1, 4.8, 5.3
12) Draw a histogram of this data. Use the number of classes and the class width that is shown on the following
blank graph:
13) What is the mean of this data?
a) 2.82
b) 2.40
c) 1.50
d) 1.70
16) What is the standard deviation of this sample
data set?
a) 2.41
b) 1.50
c) 1.55
d) 4.56
14) What is the median of this data?
a) 2.40
b) 2.45
c) 2.50
d) 2.82
17) What is the variance of this data?
a) 2.41
b) 1.50
c) 1.55
d) 4.56
15) What is the mode of this data?
a) 2.45
b) 2.40
c) 1.50
d) 1.70
18) What is the skewness of this data?
a) 1.50
b) 4.50
c) 0.85
d) -1.75
More Definitions
19) When you look at the graph of a set of data and
notice that there is a pronounced tail going off to
the left, you can be pretty convinced that the data
has ________.
a) Negative skewness
b) Positive skewness
c) No skewness
22) Variables that can take on any real number value
(integer or decimal) are:
a) Discrete variables
b) Skewed variables
c) Continuous variables
d) Standard variables
20) The measures of central tendency are:
a) The mean
b) The mode
c) The median
d) All of the above
R. Gist
21) The measures of the spread or precision of the
data are:
a) The standard deviation and the variance
b) The mean and the variance
c) The skewness and the variance
d) The mean and the skewness
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Ver. D, Rev. 1
ID105 Exam 3
The Normal Curve
The set of questions below are based on the following normal curve. This particular curve
represents the scores of a large population on a standard SAT exam. The mean is 500 (=500)
and the standard deviation is 100 (=100). The percentages given below represent the
percentage of the population between the values on the horizontal axis.
23) On the standard SAT exam, Debbie scores 600.
What percentage of all people taking this test
will score higher than Debbie?
a) 0.5%
b) 2.5%
c) 16%
d) 84%
26) What is the highest grade someone else could
have and still be in the lowest 16% of everyone
taking the test?
a) 300
b) 400
c) 500
d) 600
24) Using Debbie as an example, you can say that
her grade lies at the ______ percentile.
a) 0.5 th
b) 2.5 th
c) 16 th
d) 84 th
27) What percentage of all people taking the exam
scored at least a 300?
a) 2.5%
b) 16%
c) 84%
d) 97.5%
25) What is the lowest grade someone else could
have and still be in the top 84% of all people
taking the test?
a) 300
b) 400
c) 500
d) 600
28) What percentage of all people taking the exam
scored between 400 and 600?
a) 34%
b) 68%
c) 16%
d) 2.5%
R. Gist
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Ver. D, Rev. 1
ID105 Exam 3
The Standard Normal Curve
The next set of questions is based on the standard normal curve. Use the z-score table at the
bottom of this page to answer the following questions.
29) What area is under the curve to the right of a
z-score of 0.8?
a) 0.212
b) 0.455
c) 0.500
d) 0.882
30) What area is under the curve to the right of a
negative z-score of z= -1.0?
a) 0.104
b) 0.308
c) 0.500
d) 0.841
The next set of questions is based on normally distributed data representing the age of a certain
population of 1000 individuals. The data has an average of 50 (=50) and a standard deviation
of 10 (=10). [Recall that z=(x-)/] Using the z-score table at the bottom of this page, answer
the following:
31) What percentage of the
population is above an age
of 50?
a) 20 %
b) 50 %
c) 70 %
d) 99.5%
32) What percentage of the
population is between 35
and 65 years old?
a) 6.7 %
b) 30.8 %
c) 68.0 %
d) 86.6 %
33) How many in the
population are between 35
and 65 years old?
a) About 110 individuals
b) About 278 individuals
c) About 505 individuals
d) About 866 individuals
____________________________________________________________________________
Z-Score Table
(A)
z-score
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
1.2
1.3
1.4
1.5
R. Gist
(B)
Area between z
and the mean
0.000
0.040
0.079
0.118
0.155
0.192
0.226
0.258
0.288
0.316
0.341
0.364
0.385
0.403
0.419
0.433
(C)
Area beyond
z
0.500
0.460
0.421
0.382
0.345
0.309
0.274
0.242
0.212
0.184
0.159
0.136
0.115
0.097
0.081
0.067
(A)
z-score
1.6
1.7
1.8
1.9
2.0
2.1
2.2
2.3
2.4
2.5
2.6
2.7
2.8
2.9
3.0
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(B)
Area between z and
the mean
0.445
0.455
0.464
0.471
0.477
0.482
0.486
0.489
0.492
0.494
0.495
0.496
0.497
0.498
0.499
(C)
Area
beyond z
0.055
0.045
0.036
0.029
0.023
0.018
0.014
0.011
0.008
0.006
0.005
0.004
0.003
0.002
0.001
Ver. D, Rev. 1