The document provides a series of questions and answers related to descriptive and inferential statistics, including concepts such as variable types, levels of measurement, probability distributions, and hypothesis testing. It covers various statistical methods and calculations relevant to data interpretation, investment measurement, and significance testing. Additionally, it serves as a guide for students preparing for the QNT 351 final exam.

1. QNT 351 Final Exam Answers
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QNT 351 Final Exam Answers

2. 1) The main purpose of descriptive statistics is to
A. summarize data in a useful and informative manner
B. make inferences about a population
C. determine if the data adequately represents the population
D. gather or collect data
2) The general process of gathering, organizing, summarizing, analyzing, and
interpreting data is called
A. statistics
B. descriptive statistics
C. inferential statistics
D. levels of measurement
3) The performance of personal and business investments is measured as a
percentage, return on investment. What type of variable is return on investment?
A. Qualitative
B. Continuous
C. Attribute
D. Discrete

3. 4) What type of variable is the number of robberies reported in your city?
A. Attribute
B. Continuous
C. Discrete
D. Qualitative
5) What level of measurement is the number of auto accidents reported in a given
month?
A. Nominal
B. Ordinal
C. Interval
D. Ratio
6) The names of the positions in a corporation, such as chief operating officer or
controller, are examples of what level of measurement?
A. Nominal
B. Ordinal
C. Interval
D. Ratio

4. 7) Shoe sizes, such as 7B, 10D, and 12EEE, are examples of what level of
measurement?
A. Nominal
B. Ordinal
C. Interval
D. Ratio
8) Monthly commissions of first-year insurance brokers are $1,270, $1,310, $1,680,
$1,380, $1,410, $1,570, $1,180, and $1,420. These figures are referred to as
A. a histogram
B. raw data
C. frequency distribution
D. frequency polygon
9) A small sample of computer operators shows monthly incomes of $1,950,
$1,775, $2,060, $1,840, $1,795, $1,890, $1,925, and $1,810. What are these
ungrouped numbers called?
A. Histogram
B. Class limits
C. Class frequencies
D. Raw data

5. 10) The sum of the deviations of each data value from this measure of central
location will always be 0
A. Mode
B. Mean
C. Median
D. Standard deviation
11) For any data set, which measures of central location have only one value?
A. Mode and median
B. Mode and mean
C. Mode and standard deviation
D. Mean and median
12) A sample of single persons receiving social security payments revealed these
monthly benefits: $826, $699, $1,087, $880, $839, and $965. How many
observations are below the median?
A. 0
B. 1
C. 2
D. 3

6. 13) A dot plot shows
A. the general shape of a distribution
B. the mean, median, and mode
C. the relationship between two variables
D. the interquartile range
14) The test scores for a class of 147 students are computed. What is the location
of the test score associated with the third quartile?
A. 111
B. 37
C. 74
D. 75%
15) The National Center for Health Statistics reported that of every 883 deaths in
recent years, 24 resulted from an automobile accident, 182 from cancer, and 333
from heart disease. Using the relative frequency approach, what is the probability
that a particular death is due to an automobile accident?
A. 24/883 or 0.027
B. 539/883 or 0.610
C. 24/333 or 0.072
D. 182/883 or 0.206

7. 16) If two events A and B are mutually exclusive, what does the special rule of
addition state?
A. P(A or B) = P(A) + P(B)
B. P(A and B) = P(A) + P(B)
C. P(A and/or B) = P(A) + P(B)
D. P(A or B) = P(A) – P(B)
17) A listing of all possible outcomes of an experiment and their corresponding
probability of occurrence is called a
A. random variable
B. probability distribution
C. subjective probability
D. frequency distribution
18) The shape of any uniform probability distribution is
A. negatively skewed
B. positively skewed
C. rectangular
D. bell shaped

8. 19) The mean of any uniform probability distribution is
A. (b – a)/2
B. (a + b)/2
C. ? x/ ?
D. n?
20) For the normal distribution, the mean plus and minus 1.96 standard deviations
will include about what percent of the observations?
A. 50%
B. 99.7%
C. 95%
D. 68%
21) For a standard normal distribution, what is the probability that z is greater than
1.75?
A. 0.0401
B. 0.0459
C. 0.4599
D. 0.9599
22) A null hypothesis makes a claim about a

9. A) Population parameter
B. sample statistic
C. sample mean
D. Type II error
23) What is the level of significance?
A. Probability of a Type II error
B. Probability of a Type I error
C. z-value of 1.96
D. Beta error
24) Suppose we test the difference between two proportions at the 0.05 level of
significance. If the computed z is -1.07, what is our decision?
A. Reject the null hypothesis
B. Do not reject the null hypothesis
C. Take a larger sample
D. Reserve judgment
25) Which of the following conditions must be met to conduct a test for the
difference in two sample means?

10. A. Data must be at least of interval scale
B. Populations must be normal
C. Variances in the two populations must be equal
D. Data must be at least of interval scale and populations must be normal
26) Which of the following statements about the two sample sizes is NOT true?
Assume the population standard deviations are equal.
A. Sample A = 11; sample B = 13
B. Sample A = 12; sample B = 14
C. Sample A = 13; sample B = 13
D. Sample A = 10; sample B = 16
27) What is the chart called when the paired data (the dependent and independent
variables) are plotted?
A. Scatter diagram
B. Bar chart
C. Pie chart
D. Histogram
28) What is the variable used to predict the value of another called?
A. Independent variable

11. B. Dependent variable
C. Correlation variable
D. Variable of determination
29) Twenty randomly selected statistics students were given 15 multiple-choice
questions and 15 open-ended questions, all on the same material. The professor
was interested in determining on which type of questions the students scored
higher. This experiment is an example of
A. a one sample test of means
B. a two sample test of means
C. a paired t-test
D. a test of proportions
30) The measurements of weight of 100 units of a product manufactured by two
parallel processes have same mean but the standard of process A is 15 while that
of B is 7. What can you conclude?
A. The weight of units in process A are grouped closer than in process B
B. The weight of units in process B are grouped closer than in process A
C. Both processes are out of control
D. More data is needed to draw a conclusion
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