Download Exam 2 (Ch.3-4) Preparation

Statistics / Exam 2 Preparation /
Ch. 3,4
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers
the question.
1) The heights of ten female students (in inches) in a college math class are listed below.
Find the mean.
65
66
67
66
67
70
67
70
71
68
A) 67.7 inches B) 65.5 inches C) 71.1 inches D) 70.0 inches
2) The repair costs for five cars which were crashed by a safety testing organization were as
follows: $130, $140, $190, $230, and $140. Find the mean cost of repair.
A) $166 B) $186 C) $156 D) $176
3) Each year advertisers spend billions of dollars purchasing commercial time on network
sports television. In the first 6 months of 1988, advertisers spent $1.1 billion. A recent
article listed the top 10 leading spenders (in millions of dollars):
Company A $71
Company E $56.6
Company K $29.2
Company B $24.9 Company C $ 61.9
Company F $23
Company G $56.3
Company J $20.3
Company D $24.4
Company H $22.5
Calculate the mean amount spent.
A) 39.01 million dollars B) 19.84 million dollars C) 393.71 million dollars D) 50.70 million
dollars
4) The number of students enrolled in a physics class for the last ten semesters are listed
below. Find the median number of students.
65 66 67 66 67 70 67 70 71 68
A) 67 students B) 66 students C) 68 students D) 70 students
5) The median of a data set for a variable is the data value that
A) Lies in the middle of the data when the data is arranged in ascending order.
B) Appears the most often
C) Is the average, that is, the sum of all the data values of the variable divided by the number of
observations in the data set?
D) None of these
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6) The following data represents a random sample of 15 complaints registered with the
customer service department of a store. Determine the median complaint.
Other
defective product
excessive waiting time
Messy store
other
other
Messy store
other
messy store
Other
messy store
messy store
other
messy store
Defective product
A) No median B) Messy store
C) Defective product D) Excessive waiting time
7) The distribution of salaries of professional basketball players is skewed to the right.
Which measure of central tendency would be the best measure to determine the location
of the center of the distribution?
A) median B) mode C) mean D) frequency
8) If the graph of a distribution of data shows that the graph is skewed to the left then the
A) Median > Mean
B) Mean . Median
C) Mean > Median
D) No conclusion about the relative position of the mean and the median can be made
9) The commuting times of ten employees (in minutes) are listed below. Find the mode
score.
65 66 67 66 67 70 67 70 71 68
A) 67 minutes B) 65 minutes C) 66 minutes D) 68 minutes
10) Compute the range for the set of data.
6, 7, 8, 9, 10
A) 4 B) 10 C) 0.8 D) 6
11) Compute the range for the set of data. 15, 17, 15, 17, 15, 17, 15, 17
A) 2 B) 17 C) 16 D) 4
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12) The book cost (in dollars) for one semester's books are given below for a sample of five
college students. Calculate the sample variance of the book costs.
280, 120, 405, 485, 325
A) 19,007.50 B) 137.87 C) 365.00 D) 323.00
13) Find the sample standard deviation.
14, 15, 16, 17, 18
A) 1.6 B) 2.5 C) 1.3 D) 1.5
14) Find the sample standard deviation
81, 75, 44, 63, 42, 30, 64, 76, 88
A) 19.9 B) 17.8 C) 350.2 D) 315.2
15) The costs (in dollars) of 10 college math textbooks are listed below. Find the sample
standard deviation. 70 72 71 70 69 73 69 68 70 71
A) $1.49 B) $70.30 C) $5.00 D) $2.23
16) The scores from a state standardized test have a mean of 80 and a standard deviation of
10. The distribution of the scores is roughly bell shaped. Use the Empirical Rule to find
the percentage of scores that lie between 60 and 80.
A) 47.5% B) 68% C) 34% D) 95%
17) Fill in the blank. ____________ gives us a method of interpreting the standard deviation
that applies to any data set, regardless of the shape of the distribution.
A) Chebyshev’s rule B) The Empirical Rule
C) Chebyshev’s rule and the empirical rule D) none of these
18) For the following data, approximate the mean number of emails received per day.
Emails (per day)
Frequency
8-11
15
12-15
38
16-19
17
20-23
31
24-27
46
A) 19.0 B) 18.5 C) 17.5 D) 20.5
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19) A student receives test scores of 62, 83, and 91. The student’s term project score is 88
and her homework score is 76. Each test is worth 20% of the final grade, the term project
is 25% of the final grade, and the homework grade is 15% of the final grade. What is the
student’s mean score in the class?
A) 80.6 B) 76.6 C) 83.3 D) 80.0
20) For the following data set, approximate the sample standard deviation of emails per day.
Emails (per day)
8-11
Frequency
18
12-15
23
16-19
38
20-23
47
24-27
32
A) 5.1 emails B) 4.0 emails C) 25.8 emails D) 19.3 emails
21) A television station claims that the amount of advertising per hour of broadcast time has
an average of 17 minutes and a standard deviation equal to 2.2 minutes. You watch the
station for 1 hour, at a randomly selected time, and carefully observe that the amount of
advertising time is equal to 7 minutes. Calculate the z-score for this amount of
advertising time.
A) z = -4.55 B) z = 4.55 C) z = -0.28 D) z = 0.28
22) Construct a scatter diagram for the given data. Determine whether there is a positive
linear correlation, negative linear correlation, or no linear correlation.
x
-5
-3
4
1
-1
-2
0
2
3
y
11
6
-6
-1
3
4
1
-4
-5
Answer: There appears to be a negative linear correlation.
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23) A researcher determines that the linear correlation coefficient is 0.85 for a paired data set.
This indicates that there is
A) a strong positive linear correlation.
B) a strong negative linear correlation.
C) no linear correlation but that there may be some other relationship.
D) insufficient evidence to make any decision about the correlation of the data.
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24) A history instructor has given the same pretest and the same final examination each
semester. He is interested in determining if there is a relationship between the scores of
the two tests. He computes the linear correlation coefficient and notes that it is 1.15.
What does this correlation coefficient value tell the instructor?
A) The history instructor has made a computational error.
B) There is a strong positive correlation between the tests.
C) There is a strong negative correlation between the tests.
D) The correlation is something other than linear.
25) Calculate the linear correlation coefficient for the data below.
x
y
0
2
9
6
4
3
5
7
17 12 0
5
9
10 7
2
A) -0.995 B) -0.671 C) -0.778 D) -0.885
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1
1
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26) A manager wishes to determine whether there is a relationship between the number of
years her sales representatives have been with the company and their average monthly
sales. The table shows the years of service for each of her sales representatives and their
average monthly sales (in thousands of dollars).
Years with
4
5
12
9
10
17
5
3
company, x
Sales, y
21 23
68
52
55
51
38
45
A) r = 0.632; no linear relation exists B) r = 0.632; linear relation exists
13
110
C) r = 0.717; linear relation exists D) r = 0.717; no linear relation exists
27) Find the equation of the regression line for the given data.
x
-5 -3 4
1
-1 -2 0
2
3
-4
y
-10 -8 9
1
-2 -6 -1 3
6
-8
A) ŷ = 2.097x - 0.552 B) ŷ = 0.522x - 2.097 C) ŷ = 2.097x + 0.552 D) ŷ = -0.552x + 2.097
28) A residual is the difference between
A) the observed value of y and the predicted value of y.
B) the observed value of x and the predicted value of x.
C) the observed value of y and the predicted value of x.
D) the observed value of x and the predicted value of y.
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29) Use the regression equation to predict the value of y for x = -1.5.
x
y
-5
-3
4
1
-1
-2
0
-10 -8
9
1
-2
-6
-1
A) -3.697 B) -2.593 C) 2.925 D) 1.269
2
3
3
6
-4
-8
13) The coefficient of correlation between x and y is r = 0.59. Calculate the coefficient of
determination R².
A) 0.35 B) 0.59 C) 0.41 D) 0.65
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