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Question 1
Which of the following is not a characteristic of the normal probability distribution?
Answer
The graph of the curve is the shape of a rectangle
The total area under the curve is always equal to 1.
99.72% of the time the random variable assumes a value within plus or minus three standard deviations of its mean
The mean is equal to the median, which is also equal to the mode.
Question 2
A manufacturer wants to estimate the proportion of defective items that are produced by a certain machine. A random sample of 50 items is taken. Which Excel function would not be appropriate to construct a confidence interval estimate?
Answer (I feel this question is a bit ambiguous. The answer depends upon in what form data is given. I have chosen the best answer)
NORMSINV
COUNTIF
STDEV
All are appropriate.
Question 3
The expected value of the random variable is
Answer
s
the standard error
the sample size
the population mean
Question 4
Ordinary arithmetic operations are meaningful
Answer
only with categorical data
only with quantitative data
either with quantitative or categorical data
with rank data
Question 5
It is known that the population variance equals 484. With a 0.95 probability, the sample size that needs to be taken to estimate the population mean if the desired margin of error is 5 or less is
Answer
25
74
189
75
Question 6
In a sample of 800 students in a university, 160, or 20%, are Business majors. Based on the above information, the school's paper reported that "20% of all the students at the university are Business majors." This report is an example of
Answer
a sample
a population
statistical inference
descriptive statistics
Question 7
The control limits for an x-bar chart are how many standard deviations above and below the process mean?
Answer
one
two
three
four
Question 8
A measure of the strength of the relationship between two variables is the
Answer
coefficient of determination
slope b1 of the estimated regression line
standard error of the estimate
correlation coefficient
Question 9
When the data have the properties of interval data and the ratio of two values is meaningful, the variable has which scale of measurement?
Answer
nominal
ordinal
interval
ratio
Question 10
If the cost of a Type I error is high, a smaller value should be chosen for the
Answer
critical value
confidence coefficient
level of significance
test statistic
Question 11
If the data distribution is symmetric, the skewness is
Answer
0
.5
1
None of the other answers is correct.
Question 12
Exhibit 10-3
A statistics teacher wants to see if there is any difference in the abilities of students enrolled in statistics today and those enrolled five years ago. A sample of final examination scores from students enrolled today and from students enrolled five years ago was taken. You are given the following information.
Today Five Years Ago
82 88
s2 112.5 54
n 45 36
Refer to Exhibit 10-3. The 95% confidence interval for the difference between the two population means is
Answer
-9.92 to -2.08
-3.92 to 3.92
-13.84 to 1.84
-24.228 to 12.23
Question 13
Exhibit 3-2
A researcher has collected the following sample data. The mean of the sample is 5.
3 5 12 3 2
Refer to Exhibit 3-2. The interquartile range is
Answer
1
2
10
12
Question 14
A sample of five Fortune 500 companies showed the following revenues ($ millions): 7505.0, 2904.7, 7208.4, 6819.0, and 19500.0. Based on this information, which of the following statements is correct?
Answer
An estimate of the average revenue for all Fortune 500 companies is 8787.42 ($ millions).
The average revenue for all Fortune 500 companies is 8787.42 ($ millions).
Over half of all Fortune 500 companies earn at least 7208.4 ($ millions) in revenues.
If five other Fortune 500 companies were chosen, the average revenue would be 8787.42 ($ millions).
Question 15
For the standard normal probability distribution, the area to the left of the mean is
Answer
-0.5
0.5
any value between 0 to 1
1
Question 16
For any continuous random variable, the probability that the random variable takes on exactly a specific value is
Answer
1.00
0.50
any value between 0 to 1
zero
Question 17
Excel's __________ can be used to construct a frequency distribution for qualitative data.
Answer
DISTRIBUTION function
SUM function
FREQUENCY function
COUNTIF function
Question 18
Excel's NORMSINV function can be used to compute
Answer
cumulative probabilities for a standard normal z value
the standard normal z value given a cumulative probability
cumulative probabilities for a normally distributed x value
the normally distributed x value given a cumulative probability
Question 19
The interquartile range is the difference between the
Answer
first and second quartiles
first and third quartiles
second and third quartiles
second and fourth quartiles
Question 20
Independent simple random samples are taken to test the difference between the means of two populations whose variances are not known. The sample sizes are n1 = 32 and n2 = 40. The correct distribution to use is the
Answer
binomial distribution
t distribution with 72 degrees of freedom
t distribution with 71 degrees of freedom
t distribution with 70 degrees of freedom
Question 21
Which of the following is an example of qualitative data?
Answer
social security number
score on a multiple-choice exam
height, in meters, of a diving board
number of square feet of carpet
Question 22
A frequency distribution is
Answer
a tabular summary of a set of data showing the fraction of items in each of several nonoverlapping classes
a graphical form of representing data
a tabular summary of a set of data showing the number of items in each of several nonoverlapping classes
a graphical device for presenting categorical data
Question 23
A tabular summary of a set of data showing the fraction of the total number of items in several nonoverlapping classes is a
Answer
frequency distribution.
relative frequency distribution.
frequency.
cumulative frequency distribution.
Question 24
Exhibit 2-3
The number of sick days taken (per month) by 200 factory workers is summarized below.
Number of Days Frequency
0 - 5 120
6 - 10 65
11 - 15 14
16 - 20 1
Refer to Exhibit 2-3. The number of workers who took more than 10 sick days per month
Answer
was 15
was 200
was 185
was 65
Question 25
A graphical presentation of a frequency distribution, relative frequency distribution, or percent frequency distribution of quantitative data constructed by placing the class intervals on the horizontal axis and the frequencies on the vertical axis is a
Answer
histogram
bar graph
stem-and-leaf display
pie chart
Question 26
The sample statistic s is the point estimator of
Answer
m
s
Question 27
The birth weight of newborns, measured in grams, is an example of
Answer
categorical data
either categorical or quantitative data
neither categorical nor quantitative data
quantitative data
Question 28
A control chart that is used to monitor the range of the measurements in a sample is
Answer
a p chart
an x-bar chart
an R chart
an np chart
Question 29
The empirical rule states that, for data having a bell-shaped distribution, the percentage of data values being within one standard deviation of the mean is approximately
Answer
33
50
68
95
Question 30
The relative frequency of a class is computed by
Answer
dividing the midpoint of the class by the sample size.
dividing the frequency of the class by the midpoint.
dividing the sample size by the frequency of the class.
dividing the frequency of the class by the sample size.
Question 31
When using Excel to calculate a p-value for an upper-tail hypothesis test, the following must be used
Answer
RAND
1 - NORMSDIST
NORMSDIST
Not enough information is given to answer this question.
Question 32
Excel's __________ function can be used to compute the mean.
Answer
MAX
AVERAGE
MEDIAN
MODE
Question 33
In regression analysis, the variable that is being predicted is the
Answer
dependent variable
independent variable
intervening variable
None of these answers is correct.
Question 34
For a standard normal distribution, a negative value of z indicates
Answer
a mistake has been made in computations, because z is always positive
the area corresponding to the z is negative
the z is to the left of the mean
the z is to the right of the mean
Question 35
Exhibit 9-3
n = 49 H0: m = 50
= 54.8 Ha: m ยน 50
s = 28
Refer to Exhibit 9-3. The test statistic equals
Answer
0.1714
0.3849
-1.2
1.2
Question 36
Exhibit 6-5
The weight of items produced by a machine is normally distributed with a mean of 8 ounces and a standard deviation of 2 ounces.
Refer to Exhibit 6-5. What is the probability that a randomly selected item will weigh more than 10 ounces?
Answer
0.3413
0.8413
0.1587
0.5000
Question 37
Exhibit 2-1
The numbers of hours worked (per week) by 400 statistics students are shown below.
Number of hours Frequency
0 - 9 20
10 - 19 80
20 - 29 200
30 - 39 100
Refer to Exhibit 2-1. The percentage of students who work at least 10 hours per week is
Answer
50%
5%
95%
100%
Question 38
A newspaper wants to estimate the proportion of Americans who will vote for Candidate A. A random sample of 1000 voters is taken. Of the 1000 respondents, 526 say that they will vote for Candidate A. Which Excel function would be used to construct a confidence interval estimate?
Answer
NORMSINV
NORMINV
TINV
INT
Question 39
Exhibit 12-2
You are given the following information about y and x.
y x
Dependent Independent
Variable Variable
5 15
7 12
9 10
11 7
Refer to Exhibit 12-2. The least squares estimate of b0 equals
Answer
-7.647
-1.3
21.4
16.41176
Question 40
From a population of 200 elements, the standard deviation is known to be 14. A sample of 49 elements is selected. It is determined that the sample mean is 56. The standard error of the mean is
Answer
3
2
greater than 2
less than 2
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