BUS 221: Exam 1
To construct a histogram, the class frequencies are plotted on the vertical or Y-axis, and either the stated limits, the true limits or the midpoints are plotted on the horizontal or X-axis.
TRUE
To infer something a population, we usually take a sample from the population.
TRUE
What does the standard deviation measure?
Dispersion
A relative frequency distribution shows the number of observations in each class.
FALSE
For a stem-and-leaf display, the leaf for the value 98 is 9.
FALSE
For a symmetrical distribution, the variance is equal to the standard deviation.
FALSE
If we select 100 persons out of 25,000 registered voters and ask them about candidates and issues, the 100 persons are referred to as the population.
FALSE
In constructing a frequency distribution, you should try to have open-ended classes such as "Under $100" and "$1,000 and over".
FALSE
In general, we should construct a frequency distribution so that there are either 4 or 24 classes.
FALSE
The coefficient of skewness is computed by dividing the standard deviation by the median and multiplying the quotient by 100.
FALSE
The mean deviation is the mean of the sum of deviations of each of the actual values from the arithmetic mean of the actual values.
FALSE
The orders that runners finish in a race would be an example of continuous data.
FALSE
The word descriptive statistics and inferential statistics can be used interchangeably.
FALSE
What is the following table called? 20 up to 30 ... 16 30 up to 40 ... 25 40 up to 50 ... 51
Frequency distribution
Which measure of central location has a sum of zero deviations when each value in a set of data is subtracted from the average of the set of data?
Mean
What do the quartile deviation and the interquartile range describe?
Middle 50% of the observations
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:
Raw data
The main purpose of descriptive statistics is to:
Summarize data in a useful and informative manner.
The median can be determined for any set of interval-level data.
TRUE
The midpoint of a class, which is also called a class mark, is halfway between the lower and upper limits.
TRUE
The mode is the value of the observation that appears most frequently.
TRUE
The number of children in a family is a discrete variable.
TRUE
The range cannot be computed for data grouped in a frequency distribution having an open end.
TRUE
Three quartiles divide a set of data into four quarters.
TRUE
In a scatter diagram, we describe the relationship between
Two variables measured at the interval or ratio level
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.
The principal difference between the interval and ratio scale of measurement is that the ratio scale has a meaningful
zero point
The monthly salaries of a sample of 100 employees were rounded to the nearest ten dollars. They ranged from a low of $1,040 to a high of $1,720. If we want to condense the data into seven classes, what is the most convenient class interval?
$100
If the sample variance for a frequency distribution consisting of hourly wages was computed to be 10, what is the sample standard deviation?
$3.16
The U.S. Federal Aviation Administration reported that passenger revenues on international flights increased from $528 million in 1981 to $5,100 million in 2004. What is the geometric mean annual percent increase in international passenger revenues?
10.4
A sample of the daily production of transceivers was organized into the following distribution. Assuming that the true class limits are 79.5-89.5 and so on, what is the mean daily production?
105.9
What is the approximate mean for the following grouped data?
124.5
What is the approximate mode for the following grouped data? The weights of a sample of 100 boxes being shipped by Air France from New York to Paris are:
137.5
A survey of passengers on domestic flights revealed these miles: What is the range (in miles)?
2,400
Referring to the frequency distribution given under Queston 19, what is the relative frequency of those salespersons who earn more than $1,599?
30.8%
The test scores for a class of 147 students are computed. Pick an answer (Test score) below that is associated with the second quartile?
43
A group of 100 students were surveyed about their interest in a new International Studies program. Interest was measured in terms of high, medium, or low. 30 students responded high interest; 50 students responded medium interest; 40 students responded low interest. What is the relative frequency of students with high interest?
Cannot be determined
The branch of statistics that we draw conclusions from about the population, based on sample data is called _________________ statistics.
Inferential
What level of measurement do Centigrade and Fahrenheit temperature scales represent?
Interval
A marketing class of 50 students evaluated the instructor using the following scale: superior, good, average, poor, and inferior. The descriptive summary showed the following survey results: 2% superior, 8% good, 45% average, 45% poor, and 0% inferior.
Most students rated the instructor as poor or average.
Which word is NOT a part of the definition of descriptive statistics?
Predicting
A box plot shows the relative symmetry of a distribution.
TRUE
A class interval, which is the width of a class, can be determined by subtracting the lower limit of a class from the lower limit of the next higher class.
TRUE
A frequency distribution groups data into classes showing the number of observations in each class.
TRUE
A frequency polygon is a very useful graphic technique when comparing two or more distributions.
TRUE
A population is a collection of all individuals, objects, or measurements of interest.
TRUE
A sample is commonly a fraction of the population
TRUE
A single value that is typical or representative of a set data is referred to as a measure of central location.
TRUE
An outlier is a value in a data set that is inconsistent with the rest of the data.
TRUE
For a data set with an even number of values, the median is the arithmetic mean of the two middle values.
TRUE
If Pearson's Coefficient of Skewness is negative, then the distribution is skewed to the left.
TRUE
If we select 200 persons out of 55,000 club members and ask them about candidates and issues, the 55,000 persons are referred to as the population.
TRUE
The 2nd quartile, the 5th decile, and the 50th percentile, are the same as the median of a distribution.
TRUE
To convert a frequency distribution to a relative frequency distribution, divide each class frequency by the sum of the frequencies of all classes.
TRUE
A dot plot shows
The general shape of a distribution
A box plot shows
The relative symmetry of a distribution for a set of data
The sum of the differences between sample observations and the sample mean is
Zero
The monthly Consumer Price Index is an example of a
statistics
A bottling company offers three kinds of delivery service instant, same day and within five days. The profit per delivery varies according to the kind of delivery. The profit for an instant delivery is less than the other kinds because the driver has to go directly to a grocery store with a small load and return to the bottling plant. To find out what effect each type of delivery has on the profit picture, the company has made the following tabulation based on deliveries for the previous quarter. What is the weighted mean profit per delivery?
$97
A sample of experienced typists revealed that their mean typing speed is 87 words per minute and the median is 73. The standard deviation is 16.9 words per minute. What is the Pearson's coefficient of skewness?
+2.5
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 the Pearson's coefficient of skewness?
-0.75
What is the possible range of values for the coefficient of variation?
0% and 100%
Refering to the following distribution of commissions: What is the relative frequency for those salespersons that earn between $1,600 and $1,799?
20%
Samples of the wires coming off the production line were tested for tensile strength. The statistical results (in PSI) were: According to the Empirical Rule, the middle 95 percent of the wires tested between approximately what two values?
420 and 580
A stem and leaf diagram does lose the identity of each observation.
FALSE
The techniques used to find out something about a population, such as their average weight, based on a sample are referred to as descriptive statistics.
FALSE
There is some loss of information when raw data is tallied into a stem-and-leaf display.
FALSE
When constructing a frequency distribution, try to include overlapping class limits, such as 100 up to 201, 200 up to 301, and 300 up to 401.
FALSE
If Gallup, Harris, and other pollsters asked people to indicate their political party affiliation - Democrat, Republican or Independent, which level of data measurement would the responses represent?
Nominal
A study of the net sales of a sample of small corporations revealed that the mean net sales is $2.1 million, the median $2.4 million, the modal sales $2.6 million and the standard deviation of the distribution is $500,000. What is the Pearson's coefficient of skewness?
None of the above
When data is collected using a qualitative, nominal variable, i.e., male or female, what is true about a frequency distribution that summarizes the data?
Number of classes corresponds to number of the variable's values.
When a class interval is expressed as: 100 up to 200,
Observations with values of 200 are excluded from the class frequency
Respondents were asked, "Do you now earn more than or less than you did five years ago?" What is this level of measurement?
Ordinal
A study of the scores on an in-plant course in management principles and the years of service of the employees enrolled in the course resulted in these statistics: Mean test score was 200 with a standard deviation of 40. Mean number of years of service was 20 years with a standard deviation of 2 years. In comparing the relative dispersion of the two distributions, what are the coefficients of variation?
Test 20%, service 10%
When TV advertisements report that "2 out of 3 dentists surveyed indicated that they would recommend Brand X toothpaste to their patients," an informed consumer may question the conclusion because:
The advertisement does not include the total number of dentists surveyed.
In the calculation of the arithmetic mean for grouped data, which value is used to represent all the values in a particular class?
The class midpoint
A student was interested in a survey dealing with cigarette smoking habits of college students and collected data from an unbiased random sample of students. The data is summarized in the following table: Male: 50 Female: 75 Male who smoke: 20 Female who smoke: 25 Male who do not smoke: 30 Female who do not smoke: 50 Why is the table NOT a frequency distribution?
The classes are not mutually exclusive.
What do the mean, the median, and the mode measure?
They are measures of central tendency
The level of measurement of a teacher like this .... superior, very good, average, poor is
ordinal
In a contingency table, we describe the relationship between
two variables measured at the ordinal or nominal level Correct Answer: Correct two variables measured at the ordinal or nominal level