111 terms

# Stats Quiz 1

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True
A population is a collection of all individuals, objects, or measurements of interest.
True
The number of individuals on a flight from New York to Chicago is an example of a statistic.
True
A sample is a portion of a population of interest.
True
An ordinal level of measurement implies some sort of ranking.
True
Data classified on a nominal scale can only be classified into categories.
True
A marketing research agency was hired to test a new DVD player. Consumers rated it outstanding, very good, fair, or poor. The level of measurement for this experiment is ordinal
False
The Union of Electrical Workers of America with 9,128 members polled 362 members about a new wage package that will be submitted to management. The population is the 362 members.
False
The order that runners finish in a race would be an example of continuous data.
True
Based on a sample of 3,000 people, the civilian unemployment rate in the United States was Based on a sample of 3,000 people, the civilian unemployment rate in the United States was 5.5%. 5.5% is referred to as a statistic.
True
The principal difference between the interval and ratio scale is that the ratio scale has a meaningful zero point.
True
The number of children in a family is a discrete variable.
Tons of concrete to complete a parking lot
What is an example of a continuous variable?
Tons of concrete to complete a parking garage
Number of students in a statistics class
Zip codes of shoppers
Rankings of baseball teams in a league
When TV advertisements report "2 out of 3 dentists surveyed indicated they would recommend Brand X toothpaste to their patients," an informed consumer may question the conclusion because the
Sample was only 5 dentists.
Sample of dentists is clearly explained.
Conclusion is not illustrated with a graph.
Ordinal
A bank asks customers to evaluate the drive-thru service as good, average, or poor. Which level of measurement is this classification?
Nominal
If Gallup, Harris, and other pollsters asked people to indicate their political party affiliation as Democrat, Republican, or Independent, the data gathered would be an example of which scale of measurement?
Nominal
The members of each basketball team wear numbers on their jerseys. What scale of measurement are these numbers considered?
Continuous
What type of variable is the number of gallons of gasoline pumped by a filling station during a day?
Ordinal
The final rankings of the top 20 NCAA college basketball teams are an example of which level of measurement?
Color of ink in a pen
An example of a qualitative variable is
Number of children in a family
Weight of a person
Color of ink in a pen
Miles between oil changes
Number of miles between New York City and Chicago
Which one of the following is NOT an example of discrete data?
Number of households watching the Home Shopping Network
Number of employees reporting in sick
Number of miles between New York City and Chicago
Number of members of the Denver Lions Club
True
A frequency distribution groups data into classes showing the number of observations in each class.
False
To summarize the gender of students attending a college, the number of classes in a frequency distribution depends on the number of students.
True
In frequency distributions, classes are mutually exclusive if each individual, object, or measurement is included in only one category.
True
In a bar chart, the heights of the bars represent the frequencies in each class.
True
A class interval, or class width, can be determined by subtracting the lower limit of a class from the lower limit of the next higher class.
True
To convert a frequency distribution to a relative frequency distribution, divide each class frequency by the sum of the class frequencies.
False
To convert a frequency distribution to a relative frequency distribution, divide each class frequency by the number of classes.
True
A pie chart shows the relative frequency in each class.
True
A cumulative frequency distribution is used when we want to determine how many observations lie above or below certain values.
Upper and lower class limits must be calculated.
When data is collected using a quantitative, ratio variable, what is true about a frequency distribution that summarizes the data?
Upper and lower class limits must be calculated.
A pie chart can be used to summarize the data.
Number of classes is equal to the number of variable's values.
The "5 to the k rule" can be applied.
A pie chart can be used to summarize the data.
When data is collected using a qualitative, nominal variable, what is true about a frequency distribution that summarizes the data?
The upper and lower class limits must be calculated.
A pie chart can be used to summarize the data.
The number of classes is equal to the number of variable's values plus 2.
The "5 to the k rule" can be applied.
The number of classes corresponds to the number of a variable's values.
When data is collected using a qualitative, nominal variable (in other words, male or female), what is true about a frequency distribution that summarizes the data?
The upper and lower class limits must be calculated.
Class midpoints can be computed.
The number of classes corresponds to the number of a variable's values.
The "2 to the k rule" can be applied.
Observations with values of 200 are excluded from the class
When a class interval is expressed as 100 up to 200,
Observations with values of 100 are excluded from the class
Observations with values of 200 are included in the class
Observations with values of 200 are excluded from the class
The class interval is 99
The class frequency divided by the total frequency.
For a relative frequency distribution, relative frequency is computed as
The class width divided by class interval
The class midpoint divided by the class frequency
The class frequency divided by the class interval
The class frequency divided by the total frequency.
Percent of observations in the class
The relative frequency for a class represents the
Class width
Class midpoint
Class interval
Percent of observations in the class
Use a pie chart
A group of 100 students were surveyed about their interest in a new Economics major. Interest was measured in terms of high, medium, or low. In the study, 30 students responded high interest, 50 students responded medium interest, and 20 students responded low interest. What is the best way to illustrate the relative frequency of student interest?
Use a cumulative frequency polygon
Use a box plot
Use a pie chart
Use a frequency table
The categories are not exhaustive.
A student was studying the political party preferences of a university's student population. The survey instrument asked students to identify themselves as a Democrat or a Republican. This question is flawed because:
Students generally don't know their political preferences.
The categories are generally mutually exclusive.
The categories are not exhaustive.
Political preference is a continuous variable.
Bar chart
A student was studying the political party preferences of a university's student population. The survey instrument asked students to identify their political preference, for example, Democrat, Republican, Libertarian, or another party. The best way to illustrate the frequencies for each political preference is a __________.
Bar chart
Box plot
Histogram
Frequency polygon
Frequency
In a frequency distribution, the number of observations in a class is called the class ________.
Midpoint
Interval
Array
Frequency
To avoid a large number of empty classes
Why are unequal class intervals sometimes used in a frequency distribution?
To avoid a large number of empty classes
For the sake of variety in presenting the data
To make the class frequencies smaller
To avoid the need for midpoints
False
A set of ordinal-, interval-, or ratio-level data may only have one mode.
False
Extremely high or low scores affect the value of the median.
True
The sum of the deviations from the mean for the set of numbers 4, 9, and 5 will equal zero.
False
For any distribution, there are an equal number of values above and below the mean.
True
Variation describes the degree of dispersion in the data.
False
The mean deviation is the sum of the absolute differences between each value and the median.
True
The standard deviation is the positive square root of the variance.
False
In a company, the standard deviation of the ages of female employees is 6 years and the standard deviation of the ages of male employees is 10 years. These statistics indicate that the dispersion of age is greater for females than for males.
False
According to Chebyshev's Theorem, 75% of the observations lie within plus and minus 2.00 average mean deviations.
Mean
The sum of the deviations of each data value from this measure of central location will always be zero.
Mode
Mean
Median
Standard deviation
Mean and median
For any data set, which measures of central location have only one value?
Mode and median
Mode and mean
Mode and standard deviation
Mean and median
Mode and median
Which measures of central location are not affected by extremely small or extremely large values?
Mean and median
Mean and mode
Mode and median
Standard deviation and mean
Median
For a data set, half of the observations are always greater than the ____.
Median
Mode
Mean
Standard deviation
Mu
Which one of the following is referred to as the population mean?
µ
s
σ
χ
\$46.51
A stockbroker placed the following order for a customer:

• 50 shares of Kaiser Aluminum at \$104 a share
• 100 shares of GTE at \$25.25 a share
• 20 shares of Boston Edison at \$9.125 a share

What is the weighted arithmetic mean price per share?
\$25.25
\$79.75
\$103.50
\$46.51
54.5
The times (in minutes) that several underwriters took to review applications for similar insurance coverage are 50, 230, 52, and 57. What is the median length of time required to review an application?
54.5
141.0
97.25
109.0
Bimodal
Sometimes, a data set has two values that have the highest and equal frequencies. In this case, the distribution of the data can best be described as __________.
Symmetric
Bimodal (having two modes)
Positively skewed
Negatively skewed
It can be biased by one or two extremely small or large values
A disadvantage of using an arithmetic mean to summarize a set of data is that __________.
The arithmetic mean sometimes has two values
It can be used for interval and ratio data
It is always different from the median
It can be biased by one or two extremely small or large values
The life of Supplier B's tire is more predictable than the life of Supplier A's tires.
A purchasing agent for a trucking company is shopping for replacement tires for their trucks from two suppliers. The suppliers' prices are the same. However, Supplier A's tires have an average life of 60,000 miles with a standard deviation of 10,000 miles. Supplier B's tires have an average life of 60,000 miles with a standard deviation of 2,000 miles.
Which of the following statements is true?
The two distributions of tire life are the same.
On average, Supplier A's tires have a longer life than Supplier B's tires.
The life of Supplier B's tire is more predictable than the life of Supplier A's tires.
The dispersion of Supplier A's tire life is less than the dispersion of Supplier B's tire life.
Zero
The sum of the differences between sample observations and the sample mean is equal to _______.
Zero
The mean deviation
The range
The standard deviation
It uses absolute values.
What is a unique characteristic of the mean deviation?
It is based on only two observations.
It is based on deviations from the mean.
It uses absolute values.
It is only applied to skewed distributions.
2.4 kg
The weights of a sample of crates ready for shipment to Moscow, Russia are (in kilograms): 103, 97, 101, 106, and 103. What is the mean deviation?
0 kg
6.9 kg
102.0 kg
2.4 kg
110 and 190
The monthly amounts spent for food by families of four receiving food stamps approximates a symmetrical, normal distribution. The sample mean is \$150 and the standard deviation is \$20. Using the Empirical Rule, about 95% of the monthly food expenditures are between what two amounts?
\$100 and \$200
\$85 and \$105
\$205 and \$220
\$110 and \$190
13.9 and 14.1 inches
The distribution of a sample of the outside diameters of PVC pipes approximates a symmetrical, bell-shaped distribution. The arithmetic mean is 14.0 inches, and the standard deviation is 0.1 inches. About 68% of the outside diameters lie between what two amounts?
13.5 and 14.5 inches
13.0 and 15.0 inches
13.9 and 14.1 inches
13.8 and 14.2 inches
True
Quartiles divide a distribution into four equal parts.
False
A student scored in the 85th percentile on a standardized test. This means that the student scored lower than 85% of all students who took the test.
False
The 50th percentile of a distribution is the same as the distribution mean.
False
A box plot graphically shows the 10th and 90th percentiles.
True
The "box" in a box plot shows the interquartile range.
True
Pearson's coefficient of skewness is a measure of a distribution's symmetry.
True
If a distribution is negatively skewed, the distribution is not symmetrical and the long tail is to the left.
True
A relationship between two nominal variables is summarized by a contingency table.
Median
In a distribution, the second quartile corresponds with the __________.
Mean
Median
Mode
Variance
Cumulative frequency distribution
If a student places in the 99th percentile on an exam, she performed better than 99% of all students who completed the exam. Her performance is similar to a statement based on a __________.
Frequency table
Cumulative frequency distribution
Histogram
Pie chart
The minimum, maximum, median, first and third quartiles.
What statistics are needed to draw a box plot?
The minimum, maximum, median, first and third quartiles.
The median, mean, and standard deviation.
The median and interquartile range.
The mean and standard deviation.
50
Using the following statistics to describe a distribution of data, what is the interquartile range?

Minimum = 10
Q1 = 25
Median = 50
Q3 = 75
Maximum = 95
85
50
15
20
Symmetric
If the coefficient of skewness is equal to zero, the shape of the distribution is __________.
Negatively skewed
Symmetric
Positively skewed
Unknown
-0.75
A large oil company is studying the number of gallons of gasoline purchased per customer at self-service pumps. The mean number of gallons is 10.0, with a standard deviation of 3.0 gallons. The median is 10.75 gallons. What is Pearson's coefficient of skewness in this instance?
-1.00
-0.75
+0.75
+1.00
Two variables measured at the interval or ratio level
In a scatter diagram, we describe the relationship between __________.
Two variables measured at the ordinal level
Two variables, one measured as an ordinal variable and the other as a ratio variable
Two variables measured at the interval or ratio level
A variable measure on the interval or ratio level and time
Two variables measured at the ordinal or nominal level
In a contingency table, we describe the relationship between ________.
Two variables measured at the ordinal or nominal level
Two variables, one measured as an ordinal variable and the other as a ratio variable
Two variables measured at the interval or ratio level
A variable measure on the interval or ratio level and time
Company employees by gender and organizational title
A contingency table would be used to summarize data such as ________.
Company employees by gender and organizational title
Company employees by gender and age
Company employees by compensation and age
Company employees by compensation and years with the company
False
A dot plot is an easy way to represent the relationship between two variables.
False
The probability of rolling a 3 or 2 on a single die is an example of conditional probability.
True
The probability of rolling a 3 or 2 on a single die is an example of mutually exclusive events.
True
An individual can assign a subjective probability to an event based on the individual's knowledge about the event.
True
To apply the special rule of addition, the events must be mutually exclusive.
True
A joint probability measures the likelihood that two or more events will happen concurrently.
True
The joint probability of two independent events, A and B, is computed as P(A and B) = P(A) P(B).
True
The joint probability of two events, A and B, that are not independent is computed as P(A and B) = P(A) P(B|A).
False
A coin is tossed four times. The joint probability that all four tosses will result in a head is ¼ or 0.25.
True
If there are "m" ways of doing one thing, and "n" ways of doing another thing, the multiplication formula states that there are (m) × (n) ways of doing both.
False
A combination of a set of objects is defined by the order of the objects.
True
The complement rule states that the probability of an event not occurring is equal to one minus the probability of its occurrence.
False
If two events are mutually exclusive, then P(A and B) = P(A)P(B).
True
An illustration of an experiment is turning the ignition key of an automobile as it comes off the assembly line to determine whether or not the engine will start.
True
An illustration of an experiment is turning the ignition key of an automobile as it comes off the assembly line to determine whether or not the engine will start.
P(A or B) = P(A) + P(B)
If two events A and B are mutually exclusive, what does the special rule of addition state?
P(A or B) = P(A) + P(B)
P(A and B) = P(A) + P(B)
P(A and/or B) = P(A) + P(B)
P(A or B) = P(A) - P(B)
P(A) = 1 - P(not A)
What does the complement rule state?
P(A) = P(A) - P(B)
P(A) = 1 - P(not A)
P(A) = P(A) × P(B)
P(A) = P(A)X + P(B)
Outcome
The result of a particular experiment is called a(n) ___________.
Observation
Conditional probability
Event
Outcome
Joint probability
The probability of two or more events occurring concurrently is called a(n) _________.
Conditional probability
Empirical probability
Joint probability
Tree diagram
The special rule of multiplication
If two events are independent, then their joint probability is computed with _________.
The special rule of multiplication
The general rule of multiplication
The Bayes theorem
True
A random variable represents the outcome of an experiment.
True
The probability of a particular outcome must always be between 0.0 and 1.0 inclusive.
True
A probability distribution is a mutually exclusive and collectively exhaustive listing of experimental outcomes that can occur by chance, and their corresponding probabilities.
False
To construct a binomial probability distribution, the mean must be known.
True
To construct a binomial distribution, it is necessary to know the total number of trials and the probability of success on each trial.
False
The mean of a probability distribution is called its expected value.
0.735
Judging from recent experience, 5% of the computer keyboards produced by an automatic, high-speed machine are defective. If six keyboards are randomly selected, what is the probability that none of the keyboards are defective?
0.001
0.167
0.735
0.500
All apply.
Which of the following is correct about a probability distribution?
The sum of all possible outcomes must equal 1.0.
Outcomes must be mutually exclusive.
The probability of each outcome must be between 0.0 and 1.0 inclusive.
All apply.
0.590
Carlson Jewelers permits the return of their diamond wedding rings, provided the return occurs within two weeks of the purchase date. Their records reveal that 10% of the diamond wedding rings are returned. Five different customers buy a wedding ring. What is the probability that none of the customers return a ring?
0.250
0.073
0.590
0.500
0.031
Chances are 50-50 that a newborn baby will be a girl. For families with five children, what is the probability that all the children are girls?
0.900
0.031
0.001
0.250