Questions and Answers of Statistics Informed Decisions Using Data

IQ Test Scores in an IQ test have a bell-shaped distribution with a mean of 100 and a standard deviation of 19.(a) What percentage of people has an IQ score between 62 and 138?(b) What percentage of
A certain standardized test’s math scores have a bell-shaped distribution with a mean of 520 and a standard deviation of 119.(a) What percentage of standardized test scores is between 401 and
The weight of an organ in adult males has a bell-shaped distribution with a mean of 300 grams and a standard deviation of 45 grams.(a) About 99.7% of organs will be between what weights?(b) What
Commuting to Work The mean of the commute time to work for a resident of a certain city is 28.8 minutes. Assume that the standard deviation of the commute time is 7.1 minutes to complete parts (a)
The frequency distribution in Table 13 represents the five-year rate of return of a random sample of 40 large-blended mutual funds. Approximate the mean fiveyear rate of return.Approach Step 1
Marissa just completed her first semester in college. She earned an A in her four-hour statistics course, a B in her three-hour sociology course, an A in her three hour psychology course, a C in her
The data in Table 13 represent the five-year rate of return of a random sample of 40 large-blended mutual funds. Approximate the standard deviation of the five-year rate of return.Approach Use the
Approximate the mean and standard deviation of the five-year rate of return data in Table 13 using a TI-84 Plus C graphing calculator.Approach The steps for approximating the mean and standard
Clarissa has just completed her second semester in college. She earned a grade of B in her 4-hour linear algebra course, a grade A in her 2-hour government course, a grade of D in her 3-hour physics
In Marissa’s calculus course, attendance counts for 5% of the grade, quizzes count for 20% of the grade, exams count for 60% of the grade, and the final exam counts for 15% of the grade. Marissa
Stan and Francine want to make perfume. In order to get the right balance of ingredients for their tastes, they bought 3 ounces of rose oil at $$2.04$ per ounce, 5 ounces of ginger essence for
Determine whether the Los Angeles Angels or the Colorado Rockies had a relatively better run-producing season. The Angels scored 773 runs and play in the American League, where the mean number of
Jennifer just received the results of her SAT exam. Her SAT Mathematics score of 600 is in the 74th percentile. What does this mean?Approach The kth percentile of an observation means that k percent
The Highway Loss Data Institute routinely collects data on collision coverage claims. Collision coverage insures against physical damage to an insured individual’s vehicle. The data in Table 16
Find the quartiles of the collision coverage claims data in Table 16.Approach Use both StatCrunch and Minitab to obtain the quartiles. The steps for obtaining quartiles using a TI-83/84 Plus graphing
Determine and interpret the interquartile range of the collision claim data from Example 3.Approach Use the quartiles found by hand in Example 3. The interquartile range, IQR, is found by computing
Check the collision coverage claims data in Table 16 for outliers.Approach Follow the preceding steps. Any data value that is less than the lower fence or greater than the upper fence will be
In a certain city, the average 20 to 29 year old man is 69.8 inches tall, with a standard deviation of 3.0 inches, while the average 20 to 29 year old woman is 64.3 inches tall, with a standard
The mean finish time for a yearly amateur auto race was 185.13 minutes with a standard deviation of 0.353 minute. The winning car, driven by Perry, finished in 184.77 minutes.The previous year’s
Explain the meaning of the following percentiles.(a) The 10th percentile of the weight of males 36 months of age in a certain 10 city is 12.0 kg.(b) The 95th percentile of the length of newborn
Quartiles Violent crimes include rape, robbery, assault, and homicide. The following is a summary of the violent-crime rate (violent crimes per 100,000 population) for all states of a country in a
A home security company located in Minneapolis, Minnesota, develops a summer ad campaign with the slogan “When you leave for vacation, burglars leave for work.” According to the city of
A national news organization developed the graphic shown in Figure 22 to illustrate the change in the highest marginal tax rate effective January 1, 2013. Why might this graph be considered
The time-series graph in Figure 24 depicts the number of residents in the United States living in poverty. Why might this graph be considered misrepresentative?Approach Look for any characteristics
The bar graph illustrated in Figure 27 is a USA Today-type graph. A survey was conducted by Impulse Research for Quilted Northern Confidential in which individuals were asked how they would flush a
Soccer continues to grow in popularity as a sport in the United States. High-profile players such as Hope Solo and Landon Donovan have helped generate renewed interest in the sport at various age
Figure 30 represents the educational attainment (level of education) in 2013 of adults 25 years and older who are U.S. residents. Why might this graph be considered misrepresentative.Approach Find
The data below shows birth rate and per capita income (in thousands of 2011 dollars) from 2000 through 2012. Draw a time-series plot for both birth rate and per capita income. Comment on any
Determine whether the following variables are qualitative or quantitative.(a) Gender(b) Temperature(c) Number of days during the past week that a college student studied(d) Zip
Determine whether the quantitative variables are discrete or continuous.(a) The number of heads obtained after flipping a coin five times.(b) The number of cars that arrive at a McDonald’s
Table 1 presents a group of selected countries and information regarding these countries as of July, 2014. Identify the individuals, variables, and data in Table 1.ApproachAn individual is an object
For each of the following variables, determine the level of measurement.(a) Gender(b) Temperature(c) Number of days during the past week that a college student studied(d) Letter grade earned in your
In a national survey of high school students (grades 9 to 12), 25% of respondents reported that someone had offered them a cigarette at least once.Determine whether the underlined value is a
In a survey of a sample of 1050 teenagers, 17% said they like to watch soccer.Determine whether the underlined value is a parameter or a statistic.
Telephone interviews of 1,502 adults found that only 69% could identify the current vice-president’s voice over the phone.Determine whether the underlined value is a parameter or a statistic.
In a national survey on substance abuse, 66.4% of respondents who were full-time college students aged 18 to 22 responded that they have never used drugs.Determine whether the underlined value is a
The average score for a class of 28 students taking a calculus midterm exam was 72%.Determine whether the underlined value is a parameter or a statistic.
Favorite musical group Classify the variable as qualitative or quantitative.
Address Classify the variable as qualitative or quantitative.
Height Classify the variable as qualitative or quantitative.
Number of students at a universityClassify the variable as qualitative or quantitative.
Number of cars owned Classify the variable as qualitative or quantitative.
Miles per hour at which a car is traveling Classify the variable as qualitative or quantitative.
Phone number Classify the variable as qualitative or quantitative.
Amount of money spent on computers this year Classify the variable as qualitative or quantitative.
Number of pieces of lumber used to make a deck Determine whether the quantitative variable is discrete or continuous.
Volume of liquid in a glass Determine whether the quantitative variable is discrete or continuous.
Number of beats in a song Determine whether the quantitative variable is discrete or continuous.
Number of coins in a jar Determine whether the quantitative variable is discrete or continuous.
Number of hands folded by a player in a poker game Determine whether the quantitative variable is discrete or continuous.
Percentage of a car’s surface which is rusted Determine whether the quantitative variable is discrete or continuous.
Distance between sides of a street Determine whether the quantitative variable is discrete or continuous.
Air pressure in pounds per square inch in an automobile tire Determine whether the quantitative variable is discrete or continuous.
Birth order among siblings in a family Determine the level of measurement of each variable.
Favorite movie Determine the level of measurement of each variable.
Ages of children: 4 years, 5 years, 6 years, 7 years, and 8 years Determine the level of measurement of each variable.
Monthly temperatures: 63°F, 68°F, 73°F, 78°F, and 83°F Determine the level of measurement of each variable.
A polling organization contacts 2141 male university graduates who have a white-collar job and asks whether or not they had received a raise at work during the past 4 months.A research objective is
A quality-control manager randomly selects 70 bottles of ketchup that were filled on July 17 to assess the calibration of the filling machine.A research objective is presented. For each, identify the
The following data relate to the characteristics of high-definition televisions A through E.Identify the individuals, variables, and data corresponding to the variables. Determine whether each
A study conducted by researchers was designed “to determine if application of duct tape is as effective as cryotherapy in the treatment of common warts.” The researchers randomly divided 70
Satisfaction level and Diabetes Researchers wanted to determine if there was an association between the level of satisfaction of an individual and their risk of diabetes. The researchers studied 1678
Researchers wanted to determine if there was an association between daily pomegranate consumption and the occurrence of high cholesterol. The researchers looked at 94,059 women and asked them to
A web page design firm has two designs for an online hardware store. To determine the more effective design, the firm uses one page with only teenage visitors and a second page with only adult
Sophia has four tickets to a concert. Six of her friends, Yolanda, Michael, Kevin, Marissa, Annie, and Katie, have all expressed an interest in going to the concert. Sophia decides to randomly select
The accounting firm of Senese and Associates has grown. To make sure their clients are still satisfied with the services they are receiving, the company decides to send a survey out to a simple
Find a simple random sample of five clients for the problem presented in Example 2.Approach The approach is similar to that given in Example 2.Step 1 Obtain the frame and assign the clients numbers
Course Selection A student entering a doctoral program in educational psychology is required to select three courses from the list of courses provided as part of his or her program.EPR 639,
The president of DePaul University wants to conduct a survey to determine the community’s opinion regarding campus safety. The president divides the DePaul community into three groups: resident
The manager of Kroger Food Stores wants to measure the satisfaction of the store’s customers. Design a sampling technique that can be used to obtain a sample of 40 customers.Approach A frame of
A sociologist wants to gather data regarding household income within the city of Boston. Obtain a sample using cluster sampling.Approach The city of Boston can be set up so that each city block is a
Systematic Sample The human resource department at a certain company wants to conduct a survey regarding worker benefits. The department has an alphabetical list of all 5746 employees at the company
For a poll of voters regarding a referendum calling for a national value-added tax, design a sampling method to obtain the individuals in the sample. Be sure to support your choice. Which sampling
A pharmaceutical company wants to conduct a survey of 40 individuals who have high cholesterol. The company has obtained a list from primary care physicians throughout the country of 6000 individuals
The owner of a shopping mall wishes to expand the number of shops available in the food court. He has a market researcher survey the first 100 customers who come into the food court during lunch to
An abortion rights advocate wants to estimate the percentage of people who favour opening abortion clinics. She conducts a nationwide survey of 1680 randomly selected adults 18 years and older. The
A polling organization conducts a study to estimate the percentage of households that have both parents sharing equally in household chores. It mails a questionnaire to 1228 randomly selected
Suppose you are conducting a survey regarding violence in hockey in a youth hockey league. You obtain a cluster sample of 10 hockey teams within a youth hockey league and sample all hockey players in
Surveys tend to suffer from low response rates. Based on past experience, a researcher determines that the typical response rate for an e-mail survey is 30%. She wishes to obtain a sample of 300
Consider the two questions shown below.(a) What is your favorite sport?(b) How much fruit do you eat in a week?Will the order in which the questions are asked affect the survey results? If so, what
A poll is being conducted on a college campus to obtain a sample of the population of an entire country.What is the frame for this type of sampling? Who would be excluded from the survey and how
Suppose a surveyor wants to conduct a phone survey about a new car. She plans to take a simple random sample. However, some people do not want to participate. Do you believe this can affect the
During every election in a particular region, pollsters conduct exit polls to help determine which candidate people voted for. During the most recent election, pollsters incorrectly predicted
Lipitor is a cholesterol-lowering drug made by Pfizer. In the Collaborative Atorvastatin Diabetes Study (CARDS), the effect of Lipitor on cardiovascular disease was assessed in 2838 subjects, ages 40
A farmer wishes to determine the optimal level of a new fertilizer on his soybean crop. Design an experiment that will assist him.Approach Follow the steps for designing an experiment.
An educational psychologist wants to determine whether listening to music has an effect on a student’s ability to learn. Design an experiment to help the psychologist answer the question.Approach
Suppose that the 60 soybean plants were actually two different varieties: 30 Chemgro soybean plants and 30 Pioneer soybean plants and that the two varieties have different yields. Design an
To help assess student learning in her music theory courses, a music professor at a community college implemented pre- and post-tests for her music theory students.A knowledge-gained score was
A physician wanted to compare two types of pain relief. One is medication and the other is using pressure points. To test whether medication relieves pain faster, they have 10 migraine sufferers
Designing an Experiment Researchers wish to know if there is a link between hypertension (high blood pressure) and consumption of sugar. Past studies have indicated that the consumption of fruits
A physical therapist wants to determine types of rehabilitation required by her patients. To do so, she obtains a simple random sample of 30 of her patients and records the body part requiring
Using the summarized data in Table 2, construct a relative frequency distribution.Approach Add all the frequencies, and then use Formula (1) to compute the relative frequency of each category of
Use the data summarized in Table 3 to construct a frequency bar graph and a relative frequency bar graph.Approach Use a horizontal axis to indicate the categories of the data (body parts) and a
Use a statistical spreadsheet to construct a frequency or relative frequency bar graph for the data in Example 1.Approach We will use Excel to construct the frequency and relative frequency bar
The data in Table 4 represent the educational attainment in 1990 and 2013 of adults 25 years and older who are residents of the United States. The data are in thousands. So 39,344 represents
The data presented in Table 6 represent the educational attainment of residents of the United States 25 years or older in 2013, based on data obtained from the U.S. Census Bureau. The data are in
A national survey asked people, “How often do you have dinner outside instead of at home?” The frequencies were as follows.(a) Construct a relative frequency distribution.(b) What percentage of
An airline offers discounted flights from Atlanta to five American cities. Below is a frequency distribution of the number of tickets purchased for each location based on a random sample of purchased
On the basis of a population survey, there were 85.2 million males and 92.4 million females aged 25 years old or older in a certain country. The educational attainment of the males and females is
The manager of a Wendy’s fast-food restaurant wants to know the typical number of customers who arrive during the lunch hour. The data in Table 8 represent the number of customers who arrive at

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