ID105 Practice Exam 3
The next set of questions uses the following set of data points taken from a discrete population:
1, 1, 2, 2, 2, 3, 3, 4, 4, 5, 6.
1) Make a bar graph of this data using the blank graph provided.
2) What is the mean of this distribution?
a) 11
b) 3
c) 2.5
d) 2
5) What is the standard deviation of this
sample (not population) data set?
a) 0.62
b) 2.6
c) 3.00
d) 1.61
3) What is the median of this distribution?
a) 11
b) 3
c) 2.5
d) 2
4) What is the mode of this distribution?
a) 11
b) 3
c) 2.5
d) 2
6) What is the variance of this distribution?
a) 0.62
b) 2.6
c) 3.00
d) 1.61
7) What is the skewness of this
distribution?
a) 0.62
b) 1.00
c) -0.81
d) 0.00
Definitions
8) A set of classes or groups based on absolute mathematical value for which a meaningful zero
value exists (example: height, age):
a) A nominal scale
b) An ordinal scale
c) An interval scale
d) A ratio scale
9) A measure of the symmetry of the data about the mean is:
a) The standard deviation
b) The median
c) The skewness
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Ver C, Rev. 1
ID105 Practice Exam 3
The next set of questions is taken from the following set of data which comes from a population
which is continuously distributed:
1.3, 1.9, 2.1, 3.1, 3.8, 3.8, 4.4, 4.5, 5.1, 5.3
10) Draw a histogram of this data. Use the number of classes and the class width that is shown
on the following blank graph:
11) What is the mean of this data?
a) 3.50
b) 3.80
c) 3.45
d) 3.53
14) What is the standard deviation of this
sample (not population) data set?
a) 1.50
b) 1.55
c) 1.92
d) 1.39
12) What is the median of this data?
a) 3.50
b) 3.80
c) 3.45
d) 3.53
15) What is the variance of this data?
a) 1.50
b) 1.55
c) 1.92
d) 1.39
13) What is the mode of this data?
a) 3.50
b) 3.80
c) 3.45
d) 3.53
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16) What is the skewness of this data?
a) 1.50
b) -4.10
c) 0.022
d) -1.75
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Ver C, Rev. 1
ID105 Practice Exam 3
The next set of questions is based on the following normal curve. The curve below represents
the results of a large population on a particular exam. The mean on the exam was 70 (=70).
The standard deviation on the exam was 5 (=5). Use the percentages given here.
17) Chuck scores 80. What percentage of all
people taking this test will score higher
than Chuck?
a) 0.5%
b) 2.5%
c) 16%
d) 84%
20) What is the highest grade someone else
could have and still be in the bottom
50% of everyone taking the exam?
a) 65
b) 70
c) 75
d) 80
18) Using Chuck as an example, you can
say that his grade lies at the ______
percentile.
a) 2.5 th
b) 16 th
c) 84 th
d) 97.5 th
21) What percentage of all people taking the
exam scored at least a 60?
a) 2.5%
b) 16%
c) 84%
d) 97.5%
19) What is the lowest grade someone else
could have and still be in the top 16% of
all people taking the exam?
a) 60
b) 65
c) 70
d) 75
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22) What percentage of all people taking the
exam scored between 60 and 80?
a) 47.5%
b) 95%
c) 68%
d) 81.5%
Ver C, Rev. 1
ID105 Practice Exam 3
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. (Recall that z=(x-)/)
23) What area is under the curve to the left of a
negative z-score of z=-0.4?
a) 0.212
b) 0.155
c) 0.345
d) 0.933
24) What area is under the curve to the left of a zscore of z= 1.6?
a) 0.055
b) 0.445
c) 0.500
d) 0.945
The next set of questions is based on normally distributed (fictional) data. The population
represents the household incomes in the state of Colorado. The average income was $50,000
(=50000). The standard deviation of incomes was $10000 (=10000). Using the z-score table
provided, answer the following:
25) What percentage of the population earned more
than $55000?
a) 10.4%
b) 30.9 %
c) 50 %
d) 68.8 %
27) What percentage of the population earned
between the average income and $55000?
a) 40 %
b) 30.8 %
c) 27.5 %
d) 19.2 %
26) If the population represented was 1.5 million
households, how many households earned more
than $55000?
a) 1 million
b) 0.84 million
c) 0.46 million
d) 0.15 million
28) What percentage of the population earned
between $35000 and $55000?
a) 6.7 %
b) 19.2 %
c) 50 %
d) 62.5 %
____________________________________________________________________________
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
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(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 C, Rev. 1