ID105 Practice Exam 3
The next seven questions all use 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.
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
2) What is the mean of this distribution?
a) 11
b) 3
c) 2.5
d) 2
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
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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
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Spring 2006
ID105 Practice Exam 3
The next seven questions are all 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
8) Draw a histogram of this data. Use the number of classes and the class width that is shown
on the following blank graph:
12) What is the standard deviation of this
sample (not population) data set?
a) 1.50
b) 1.55
c) 1.92
d) 1.39
9) What is the mean of this data?
a) 3.50
b) 3.80
c) 3.45
d) 3.53
10) What is the median of this data?
a) 3.50
b) 3.80
c) 3.45
d) 3.53
13) What is the variance of this data?
a) 1.50
b) 1.55
c) 1.92
d) 1.39
11) What is the mode of this data?
a) 3.50
b) 3.80
c) 3.45
d) 3.53
e)
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14) What is the skewness of this data?
a) 1.50
b) -4.10
c) 0.022
d) -1.75
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Spring 2006
ID105 Practice Exam 3
The next 6 questions are 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 (μ=70). The
standard deviation on the exam was 5 (σ=5). Use the percentages given here.
15) 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%
18) 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
16) 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
19) What percentage of all people taking the
exam scored at least a 60?
a) 2.5%
b) 16%
c) 84%
d) 97.5%
17) 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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20) What percentage of all people taking the
exam scored between 60 and 80?
a) 47.5%
b) 95%
c) 68%
d) 81.5%
Spring 2006
ID105 Practice Exam 3
The next 6 questions are based on normally distributed (fictional) data. The population
represents the household incomes in the state of Colorado. The average income was $50,000
(μ=50000). The standard deviation of incomes was $10000 (σ=10000). Using the z-score table
provided, answer the following:
21) What percentage of the population earned less than $50000?
a) 40 %
b) 45 %
c) 50 %
d) 60 %
22) What percentage of the population earned more than $55000?
a) 10.4%
b) 30.8 %
c) 50 %
d) 68.8 %
23) 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
24) What percentage of the population earned less than $35000?
a) 6.7 %
b) 19.2 %
c) 50 %
d) 75.6 %
25) What percentage of the population earned between the average income and $55000?
a) 40 %
b) 30.8 %
c) 27.5 %
d) 19.2 %
26) What percentage of the population earned between $35000 and $55000?
a) 6.7 %
b) 19.2 %
c) 50 %
d) 62.5 %
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