For each word problem, use a solution sheet to solve the hypothesis test problem. Go to The Table of Contents 14. Appendix for the chi-square solution sheet. Round expected frequency to two decimal places.
Exercise 2
A 6-sided die is rolled 120 times. Fill in the expected frequency column. Then, conduct a hypothesis test to determine if the die is fair. The data below are the result of the 120 rolls.
| Face Value | Frequency | Expected Frequency |
|---|---|---|
| 1 | 15 | |
| 2 | 29 | |
| 3 | 16 | |
| 4 | 15 | |
| 5 | 30 | |
| 6 | 15 |
Exercise 3
The marital status distribution of the U.S. male population, age 15 and older, is as shown below. (Source: U.S. Census Bureau, Current Population Reports)
| Marital Status | Percent | Expected Frequency |
|---|---|---|
| never married | 31.3 | |
| married | 56.1 | |
| widowed | 2.5 | |
| divorced/separated | 10.1 |
Suppose that a random sample of 400 U.S. young adult males, 18 – 24 years old, yielded the following frequency distribution. We are interested in whether this age group of males fits the distribution of the U.S. adult population. Calculate the frequency one would expect when surveying 400 people. Fill in the above table, rounding to two decimal places.
| Marital Status | Frequency |
|---|---|
| never married | 140 |
| married | 238 |
| widowed | 2 |
| divorced/separated | 20 |
The next two questions refer to the following information. The columns in the chart below contain the Race/Ethnicity of U.S. Public Schools for a recent year, the percentages for the Advanced Placement Examinee Population for that class and the Overall Student Population. (Source: http://www.collegeboard.com). Suppose the right column contains the result of a survey of 1000 local students from that year who took an AP Exam.
| Race/Ethnicity | AP Examinee Population | Overall Student Population | Survey Frequency |
|---|---|---|---|
| Asian, Asian American or Pacific Islander | 10.2% | 5.4% | 113 |
| Black or African American | 8.2% | 14.5% | 94 |
| Hispanic or Latino | 15.5% | 15.9% | 136 |
| American Indian or Alaska Native | 0.6% | 1.2% | 10 |
| White | 59.4% | 61.6% | 604 |
| Not reported/other | 6.1% | 1.4% | 43 |
Exercise 4
Perform a goodness-of-fit test to determine whether the local results follow the distribution of the U. S. Overall Student Population based on ethnicity.
Exercise 5
Perform a goodness-of-fit test to determine whether the local results follow the distribution of U. S. AP Examinee Population, based on ethnicity.
Exercise 6
The City of South Lake Tahoe, CA, has an Asian population of 1419 people, out of a total population of 23,609 (Source: U.S. Census Bureau). Suppose that a survey of 1419 self-reported Asians in Manhattan, NY, area yielded the data in the table below. Conduct a goodness of fit test to determine if the self-reported sub-groups of Asians in the Manhattan area fit that of the Lake Tahoe area.
| Race | Lake Tahoe Frequency | Manhattan Frequency | |
|---|---|---|---|
| Asian Indian | 131 | 174 | |
| Chinese | 118 | 557 | |
| Filipino | 1045 | 518 | |
| Japanese | 80 | 54 | |
| Korean | 12 | 29 | |
| Vietnamese | 9 | 21 | |
| Other | 24 | 66 |
The next two questions refer to the following information: UCLA conducted a survey of more than 263,000 college freshmen from 385 colleges in fall 2005. The results of student expected majors by gender were reported in The Chronicle of Higher Education (2/2/2006). Suppose a survey of 5000 graduating females and 5000 graduating males was done as a follow-up last year to determine what their actual major was. The results are shown in the tables for Exercises 7 and 8. The second column in each table does not add to 100% because of rounding.
Exercise 7
Conduct a hypothesis test to determine if the actual college major of graduating females fits the distribution of their expected majors.
| Major | Women - Expected Major | Women - Actual Major |
|---|---|---|
| Arts & Humanities | 14.0% | 670 |
| Biological Sciences | 8.4% | 410 |
| Business | 13.1% | 685 |
| Education | 13.0% | 650 |
| Engineering | 2.6% | 145 |
| Physical Sciences | 2.6% | 125 |
| Professional | 18.9% | 975 |
| Social Sciences | 13.0% | 605 |
| Technical | 0.4% | 15 |
| Other | 5.8% | 300 |
| Undecided | 8.0% | 420 |
Exercise 8
Conduct a hypothesis test to determine if the actual college major of graduating males fits the distribution of their expected majors.
| Major | Men - Expected Major | Men - Actual Major |
|---|---|---|
| Arts & Humanities | 11.0% | 600 |
| Biological Sciences | 6.7% | 330 |
| Business | 22.7% | 1130 |
| Education | 5.8% | 305 |
| Engineering | 15.6% | 800 |
| Physical Sciences | 3.6% | 175 |
| Professional | 9.3% | 460 |
| Social Sciences | 7.6% | 370 |
| Technical | 1.8% | 90 |
| Other | 8.2% | 400 |
| Undecided | 6.6% | 340 |
Exercise 9
A recent debate about where in the United States skiers believe the skiing is best prompted the following survey. Test to see if the best ski area is independent of the level of the skier.
| U.S. Ski Area | Beginner | Intermediate | Advanced |
|---|---|---|---|
| Tahoe | 20 | 30 | 40 |
| Utah | 10 | 30 | 60 |
| Colorado | 10 | 40 | 50 |
Exercise 10
Car manufacturers are interested in whether there is a relationship between the size of car an individual drives and the number of people in the driver’s family (that is, whether car size and family size are independent). To test this, suppose that 800 car owners were randomly surveyed with the following results. Conduct a test for independence.
| Family Size | Sub & Compact | Mid-size | Full-size | Van & Truck |
|---|---|---|---|---|
| 1 | 20 | 35 | 40 | 35 |
| 2 | 20 | 50 | 70 | 80 |
| 3 - 4 | 20 | 50 | 100 | 90 |
| 5+ | 20 | 30 | 70 | 70 |
Exercise 11
College students may be interested in whether or not their majors have any effect on starting salaries after graduation. Suppose that 300 recent graduates were surveyed as to their majors in college and their starting salaries after graduation. Below are the data. Conduct a test for independence.
| Major | < $50,000 | $50,000 - $68,999 | $69,000 + |
|---|---|---|---|
| English | 5 | 20 | 5 |
| Engineering | 10 | 30 | 60 |
| Nursing | 10 | 15 | 15 |
| Business | 10 | 20 | 30 |
| Psychology | 20 | 30 | 20 |
Exercise 12
Some travel agents claim that honeymoon hot spots vary according to age of the bride and groom. Suppose that 280 East Coast recent brides were interviewed as to where they spent their honeymoons. The information is given below. Conduct a test for independence.
| Location | 20 - 29 | 30 - 39 | 40 - 49 | 50 and over |
|---|---|---|---|---|
| Niagara Falls | 15 | 25 | 25 | 20 |
| Poconos | 15 | 25 | 25 | 10 |
| Europe | 10 | 25 | 15 | 5 |
| Virgin Islands | 20 | 25 | 15 | 5 |
Exercise 13
A manager of a sports club keeps information concerning the main sport in which members participate and their ages. To test whether there is a relationship between the age of a member and his or her choice of sport, 643 members of the sports club are randomly selected. Conduct a test for independence.
| Sport | 18 - 25 | 26 - 30 | 31 - 40 | 41 and over |
|---|---|---|---|---|
| racquetball | 42 | 58 | 30 | 46 |
| tennis | 58 | 76 | 38 | 65 |
| swimming | 72 | 60 | 65 | 33 |
Exercise 14
A major food manufacturer is concerned that the sales for its skinny French fries have been decreasing. As a part of a feasibility study, the company conducts research into the types of fries sold across the country to determine if the type of fries sold is independent of the area of the country. The results of the study are below. Conduct a test for independence.
| Type of Fries | Northeast | South | Central | West |
|---|---|---|---|---|
| skinny fries | 70 | 50 | 20 | 25 |
| curly fries | 100 | 60 | 15 | 30 |
| steak fries | 20 | 40 | 10 | 10 |
Exercise 15
According to Dan Lenard, an independent insurance agent in the Buffalo, N.Y. area, the following is a breakdown of the amount of life insurance purchased by males in the following age groups. He is interested in whether the age of the male and the amount of life insurance purchased are independent events. Conduct a test for independence.
| Age of Males | None | < $200,000 | $200,000 - $400,000 | $401,001 - $1,000,000 | $1,000,000 + |
|---|---|---|---|---|---|
| 20 - 29 | 40 | 15 | 40 | 0 | 5 |
| 30 - 39 | 35 | 5 | 20 | 20 | 10 |
| 40 - 49 | 20 | 0 | 30 | 0 | 30 |
| 50 + | 40 | 30 | 15 | 15 | 10 |
Exercise 16
Suppose that 600 thirty–year–olds were surveyed to determine whether or not there is a relationship between the level of education an individual has and salary. Conduct a test for independence.
| Annual Salary | Not a high school graduate | High school graduate | College graduate | Masters or doctorate |
|---|---|---|---|---|
| < $30,000 | 15 | 25 | 10 | 5 |
| $30,000 - $40,000 | 20 | 40 | 70 | 30 |
| $40,000 - $50,000 | 10 | 20 | 40 | 55 |
| $50,000 - $60,000 | 5 | 10 | 20 | 60 |
| $60,000 + | 0 | 5 | 10 | 150 |
Exercise 17
A Psychologist is interested in testing whether there is a difference in the distribution of personality types for business majors and social science majors. The results of the study are shown below. Conduct a Test of Homogeneity. Test at a 5% level of significance.
| Open | Conscientious | Extrovert | Agreeable | Neurotic | |
| Business | 41 | 52 | 46 | 61 | 58 |
| Social Science | 72 | 75 | 63 | 80 | 65 |
Exercise 18
Do men and women select different breakfasts? The breakfast ordered by randomly selected men and women at a popular breakfast place is shown below. Conduct a test of homogeneity. Test at a 5% level of significance
| French Toast | Pancakes | Waffles | Omelettes | |
| Men | 47 | 35 | 28 | 53 |
| Women | 65 | 59 | 55 | 60 |
Exercise 19
Is there a difference between the distribution of community college statistics students and the distribution of university statistics students in what technology they use on their homework? Of the randomly selected community college students 43 used a computer, 102 used a calculator with built in statistics functions, and 65 used a table from the textbook. Of the randomly selected university students 28 used a computer, 33 used a calculator with built in statistics functions, and 40 used a table from the textbook. Conduct an appropriate hypothesis test using a 0.05 level of significance.
Exercise 20
A fisherman is interested in whether the distribution of fish caught in Green Valley Lake is the same as the distribution of fish caught in Echo Lake. Of the 191 randomly selected fish caught in Green Valley Lake, 105 were rainbow trout, 27 were other trout, 35 were bass, and 24 were catfish. Of the 293 randomly selected fish caught in Echo Lake, 115 were rainbow trout, 58 were other trout, 67 were bass, and 53 were catfish. Perform the hypothesis test at a 5% level of significance.
Exercise 21
A plant manager is concerned her equipment may need recalibrating. It seems that the actual weight of the 15 oz. cereal boxes it fills has been fluctuating. The standard deviation should be at most
Exercise 22
Consumers may be interested in whether the cost of a particular calculator varies from store to store. Based on surveying 43 stores, which yielded a sample mean of $84 and a sample standard deviation of $12, test the claim that the standard deviation is greater than $15.
Exercise 23
Isabella, an accomplished Bay to Breakers runner, claims that the standard deviation for her time to run the 7 ½ mile race is at most 3 minutes. To test her claim, Rupinder looks up 5 of her race times. They are 55 minutes, 61 minutes, 58 minutes, 63 minutes, and 57 minutes.
Exercise 24
Airline companies are interested in the consistency of the number of babies on each flight, so that they have adequate safety equipment. They are also interested in the variation of the number of babies. Suppose that an airline executive believes the average number of babies on flights is 6 with a variance of 9 at most. The airline conducts a survey. The results of the 18 flights surveyed give a sample average of 6.4 with a sample standard deviation of 3.9. Conduct a hypothesis test of the airline executive’s belief.
Exercise 25
The number of births per woman in China is 1.6 down from 5.91 in 1966 (SourceWorld Bank, 6/5/12). This fertility rate has been attributed to the law passed in 1979 restricting births to one per woman. Suppose that a group of students studied whether or not the standard deviation of births per woman was greater than 0.75. They asked 50 women across China the number of births they had. Below are the results. Does the students’ survey indicate that the standard deviation is greater than 0.75?
| # of births | Frequency |
|---|---|
| 0 | 5 |
| 1 | 30 |
| 2 | 10 |
| 3 | 5 |
Exercise 26
According to an avid aquariest, the average number of fish in a 20–gallon tank is 10, with a standard deviation of 2. His friend, also an aquariest, does not believe that the standard deviation is 2. She counts the number of fish in 15 other 20–gallon tanks. Based on the results that follow, do you think that the standard deviation is different from 2? Data: 11; 10; 9; 10; 10; 11; 11; 10; 12; 9; 7; 9; 11; 10; 11
Exercise 27
The manager of "Frenchies" is concerned that patrons are not consistently receiving the same amount of French fries with each order. The chef claims that the standard deviation for a 10–ounce order of fries is at most 1.5 oz., but the manager thinks that it may be higher. He randomly weighs 49 orders of fries, which yields a mean of 11 oz. and a standard deviation of 2 oz.







Download handout (.pdf)

"Reviewer's Comments: 'I recommend this book. Overall, the chapters are very readable and the material presented is consistent and appropriate for the course. A wide range of exercises introduces […]"