All Matches
Solution Library
Expert Answer
Textbooks
Search Textbook questions, tutors and Books
Oops, something went wrong!
Change your search query and then try again
Toggle navigation
FREE Trial
S
Books
FREE
Tutors
Study Help
Expert Questions
Accounting
General Management
Mathematics
Finance
Organizational Behaviour
Law
Physics
Operating System
Management Leadership
Sociology
Programming
Marketing
Database
Computer Network
Economics
Textbooks Solutions
Accounting
Managerial Accounting
Management Leadership
Cost Accounting
Statistics
Business Law
Corporate Finance
Finance
Economics
Auditing
Ask a Question
AI Study Help
New
Search
Search
Sign In
Register
study help
mathematics
statistics
Questions and Answers of
Statistics
Under the condition that both populations have equal standard deviations (σ1 – σ2), we can pool the standard deviations and use a Student’s t distribution with degrees of freedom d.f. – n1 +
Consider two independent normal distributions. A random sample of size n1 = 20 from the –first distribution showed x1 = 12 and a random sample of size n2 = 25 from the second distribution showed x2
Locander et al. also studied the accuracy of responses on questions involving more sensitive material than voter registration. From public records, individuals were identified as having been charged
What happens if we want several confidence intervals to hold at the same time (concurrently)? Do we still have the same level of confidence we had for each individual interval?(a) Suppose we have
Athabasca Fishing Lodge is located on Lake Athabasca in northern Canada. In one of its recent brochures, the lodge advertises that 75% of its guests catch northern pike over 20 pounds. Suppose that
In the following data pairs, A represents birthrate and B represents death rate per 1000 resident population. The data are paired by counties in the Midwest. A random sample of 16 counties gave the
The following data are based on information taken from the book Navajo Architecture: Forms, History, Distributions by S. C. Jett and V. E. Spencer (University of Arizona Press). A survey of houses
In the following data pairs, A represents the cost of living index for utilities and B represents the cost of living index for transportation. The data are paired by metropolitan areas in the United
The following data are based on information from the Regis University Psychology Department. In an effort to determine if rats perform certain tasks more quickly if offered larger rewards, the
The same experimental design discussed in Problem 20 was used to test rats trained to climb a sequence of short ladders. Times in seconds for eight rats to perform this task are shown in the
Consider a hypothesis test of difference of means for two independent populations x1 and x2.(a) What does the null hypothesis say about the relationship between the two population means?(b) If the
Based on information from The Denver Post, a random sample of n1 = 12 winter days in Denver gave a sample mean pollution index of x̅1 = 43. Previous studies show that σ1 = 21. For Englewood (a
In the journal Mental Retardation, an article reported the results of a peer tutoring program to help mildly mentally retarded children learn to read. In the experiment, the mildly retarded children
Consider independent random samples from two populations that are normal or approximately normal, or the case in which both sample sizes are at least 30. Then, if σ1 and σ2 are unknown but we have
This problem is based on information taken from Life in America’s Fifty States by G. S. Thomas. A random sample of n1 = 153 people ages 16 to 19 was taken from the island of Oahu, Hawaii, and 12
A random sample of n1 = 288 voters registered in the state of California showed that 141 voted in the last general election. A random sample of n2 = 216 registered voters in the state of Colorado
Consider use of a Student’s t distribution to test the difference of means for independent populations using random samples of sizes n1 and n2.(a) Which process gives the larger degrees of freedom,
When testing m or the difference of means µ1 – µ2 from independent populations, how do we decide whether to use the standard normal distribution or a Student’s t distribution?
A comparison is made between two bus lines to determine if arrival times of their regular buses from Denver to Durango are off schedule by the same amount of time. For 51 randomly selected runs, bus
A study is made of residents in Phoenix and its suburbs concerning the proportion of residents who subscribe to Sporting News. A random sample of 88 urban residents showed that 12 subscribed, and a
The Wind Mountain archaeological site is in southwest New Mexico. Prehistoric Native Americans called Anasazi once lived and hunted small game in this region. A stemmed projectile point is an
The highway department is testing two types of reflecting paint for concrete bridge end pillars. The two kinds of paint are alike in every respect except that one is orange and the other is yellow.
In Section 5.1, we studied linear combinations of independent random variables. What happens if the variables are not independent? A lot of mathematics can be used to prove the following:Let x and y
Let x be a random variable that represents blood glucose level after a 12-hour fast. Let y be a random variable representing blood glucose level 1 hour after drinking sugar water (after the 12-hour
There are several extensions of linear regression that apply to exponential growth and power law models. Problems 22–25 will outline some of these extensions. First of all, recall that a variable
Let x = day of observation and y = number of locusts per square meter during a locust infestation in a region of North Africa.(a) Draw a scatter diagram of the (x, y) data pairs. Do you think a
Expand Your Knowledge: Logarithmic Transformations. Power Law Model When we take measurements of the same general type, a power law of the form y = axβ often gives an excellent fit to the data. A
Let x = boiler steam pressure in 100 lb/in2 and let y = critical sheer strength of boiler plate steel joints in tons/in2. We have the following data for a series of factory boilers.(a) Make the
Ocean currents are important in studies of climate change, as well as ecology studies of dispersal of plankton. Drift bottles are used to study ocean currents in the Pacific near Hawaii, the
Wolf packs tend to be large extended family groups that have a well-defined hunting territory. Wolves not in the pack are driven out of the territory or killed. In ecologically similar regions, is
Refer to the Minitab printout regarding prehistoric pottery.(a) The standard error Se of the linear regression model is given in the print out as “S.” What is the value of Se?(b) The standard
Given the linear regression equationx1 = 1.6 + 3.5x2 – 7.9x3 + 2.0x4(a) Which variable is the response variable? Which variables are the explanatory variables?(b) Which number is the constant term?
Given the linear regression equationx3 = –16.5+ 4.0x1 +9.2x4 –1.1x7(a) Which variable is the response variable? Which variables are the explanatory variables?(b) Which number is the constant
The systolic blood pressure of individuals is thought to be related to both age and weight. For a random sample of 11 men, the following data were obtained:(a) Generate summary statistics, including
Professor Gill has taught general psychology for many years. During the semester, she gives three multiple-choice exams, each worth 100 points. At the end of the course, Dr. Gill gives a
A motion picture industry analyst is studying movies based on epic novels. The following data were obtained for 10 Hollywood movies made in the past 5 years. Each movie was based on an epic novel.
All Greens is a franchise store that sells house plants and lawn and garden supplies. Although All Greens is a franchise, each store is owned and managed by private individuals. Some friends have
Let x be a random variable representing percentage change in neighborhood population in the past few years, and let y be a random variable representing crime rate (crimes per 1000 population). A
Bighorn sheep are beautiful wild animals found throughout the western United States. Data for this problem are based on information taken from The Desert Bighorn, edited by Monson and Sumner
A sociologist is interested in the relation between x = number of job changes and y = annual salary (in thousands of dollars) for people living in the Nashville area. A random sample of 10 people
Modern medical practice tells us not to encourage babies to become too fat. Is there a positive correlation between the weight x of a 1-year-old baby and the weight y of the mature adult (30 years
Dorothy Kelly sells life insurance for the Prudence Insurance Company. She sells insurance by making visits to her clients homes. Dorothy believes that the number of sales should depend, to some
Each box of Healthy Crunch breakfast cereal contains a coupon entitling you to a free package of garden seeds. At the Healthy Crunch home office, they use the weight of incoming mail to determine how
For Problems 9–19, please provide the following information.(a) What is the level of significance? State the null and alternate hypotheses.(b) Find the value of the chi-square statistic for the
For Problems 5–16, please provide the following information.(a) What is the level of significance? State the null and alternate hypotheses.(b) Find the value of the chi-square statistic for the
For Problems 5–16, please provide the following information.(a) What is the level of significance? State the null and alternate hypotheses.(b) Find the value of the chi-square statistic for the
A civil engineer has been studying the frequency of vehicle accidents on a certain stretch of interstate highway. Long-term history indicates that there has been an average of 1.72 accidents per day
A pathologist has been studying the frequency of bacterial colonies within the field of a microscope using samples of throat cultures from healthy adults. Long-term history indicates that there is
A factor in determining the usefulness of an examination as a measure of demonstrated ability is the amount of spread that occurs in the grades. If the spread or variation of examination scores is
A set of solar batteries is used in a research satellite. The satellite can run on only one battery, but it runs best if more than one battery is used. The variance s2 of lifetimes of these batteries
The following problem is based on information from Archaeological Surveys of Chaco Canyon, New Mexico, by A. Hayes, D. Brugge, and W. Judge, University of New Mexico Press. A transect is an
The following problem is based on information from an article by N. Keytz in the American Journal of Sociology (Vol. 53, pp. 470–480). Let x 5 age in years of a rural Quebec woman at the time of
The following problem is based on information taken from Accidents in North American Mountaineering (jointly published by The American Alpine Club and The Alpine Club of Canada). Let x represent the
The following problem is based on information taken from Academe, Bulletin of the American Association of University Professors. Let x represent the average annual salary of college and university
A new kind of typhoid shot is being developed by a medical research team. The old typhoid shot was known to protect the population for a mean time of 36 months, with a standard deviation of 3 months.
Jim Mead is a veterinarian who visits a Vermont farm to examine prize bulls. In order to examine a bull, Jim first gives the animal a tranquilizer shot. The effect of the shot is supposed to last
The fan blades on commercial jet engines must be replaced when wear on these parts indicates too much variability to pass inspection. If a single fan blade broke during operation, it could severely
How reliable are mutual funds that invest in bonds? Again, this depends on the bond fund you buy (see reference in Problem 9). A random sample of annual percentage returns for mutual funds holding
A new fuel injection system has been engineered for pickup trucks. The new system and the old system both produce about the same average miles per gallon. However, engineers question which system
A new thermostat has been engineered for the frozen food cases in large supermarkets. Both the old and the new thermostats hold temperatures at an average of 25oF. However, it is hoped that the new
Rothamsted Experimental Station (England) has studied wheat production since 1852. Each year, many small plots of equal size but different soil/fertilizer conditions are planted with wheat. At the
Two plots at Rothamsted Experimental Station (see reference in Problem 5) were studied for production of wheat straw. For a random sample of years, the annual wheat straw production (in pounds) from
An economist wonders if corporate productivity in some countries is more volatile than that in other countries. One measure of a company’s productivity is annual percentage yield based on total
A random sample of leading companies in South Korea gave the following percentage yields based on assets (see reference in Problem 7):Use a calculator to verify that s2 = 2.247 for these South Korean
You don’t need to be rich to buy a few shares in a mutual fund. The question is, “How reliable are mutual funds as investments?”That depends on the type of fund you buy. The following data are
Wind Mountain is an archaeological study area located in southwestern New Mexico. Pot sherds are broken pieces of prehistoric Native American clay vessels. One type of painted ceramic vessel is
Another type of painted ceramic vessel is called three-circle red-on-white (see reference in Problem 1). At four different sites in the Wind Mountain archaeological region, the number of such sherds
How productive are U.S. workers? One way to answer this question is to study annual prots per employee. A random sample of companies in computers (I), aerospace (II), heavy equipment (III), and
A random sample of companies in electric utilities (I), financial services (II), and food processing (III) gave the following information regarding annual prots per employee (units in thousands
Where are the deer? Random samples of square-kilometer plots were taken in different ecological locations of Mesa Verde National Park. The deer counts per square kilometer were recorded and are shown
Wild irises are beautiful flowers found throughout the United States, Canada, and northern Europe. This problem concerns the length of the sepal (leaf-like part covering the flower) of different
An executive at the home office of Big Rock Life Insurance is considering three branch managers as candidates for promotion to vice president. The branch reports include records showing sales
The quantity of dissolved oxygen is a measure of water pollution in lakes, rivers, and streams. Water samples were taken at four different locations in a river in an effort to determine if water
A sociologist studying New York City ethnic groups wants to determine if there is a difference in income for immigrants from four different countries during their first year in the city. She
In a study of media usage versus education level (American Demographics, Vol. 17, No. 6), an index was used to measure media usage, where a measurement of 100 represents the U.S. average. Values
In the same study described in Problem 4, media usage versus household income also was considered. The media usage indices for the various media and income levels follow.(a) List the factors and the
Does college grade point average (GPA) depend on gender? Does it depend on class (freshman, sophomore, junior, senior)? In a study, the following GPA data were obtained for random samples of college
A researcher forms three blocks of students interested in taking a history course. The groups are based on grade point average (GPA). The first group consists of students with a GPA less than 2.5,
A machine that puts corn flakes into boxes is adjusted to put an average of 15 ounces into each box, with standard deviation of 0.25 ounce. If a random sample of 12 boxes gave a sample standard
Two processes for manufacturing large roller bearings are under study. In both cases, the diameters (in centimeters) are being examined. A random sample of 21 roller bearings from the old
Two processes for manufacturing 60-watt light bulbs are under study. In both cases, the life (in hours) of the bulb before it burns out is being examined. A random sample of 18 light bulbs
Does the newspaper section in which an ad is placed make a difference in the average daily number of people responding to the ad? Is there a difference in average daily number of people responding to
The makers of Country Boy Corn Flakes are thinking about changing the packaging of the cereal in the hope of improving sales. In an experiment, ve stores of similar size in the same region sold
A consumer agency is investigating the blowout pressures of Soap Stone tires. A Soap Stone tire is said to blow out when it separates from the wheel rim due to impact forces usually caused by hitting
Anela is a computer scientist who is formulating a large and complicated program for a type of data processing. She has three ways of storing and retrieving data: cloud storage, disk, or hard drive.
Professor Stone complains that students’ teacher ratings depend on the grade students receive. In other words, according to Professor Stone, a teacher who gives good grades gets good ratings, and a
How do the average weekly incomes of lawyers and architects compare? A random sample of 18 regions in the United States gave the following information about average weekly incomes (in dollars)Does
Is the high school dropout rate higher for males or females? A random sample of population regions gave the following information about percentage of 15- to 19-year-olds who are high school
The Focus Problem at the beginning of this chapter asks you to use a sign test with a 5% level of significance to test the claim that the overall temperature distribution of Madison, Wisconsin, is
Asian economies impact some of the world’s largest populations. The growth of an economy has a big influence on the everyday lives of ordinary people. Are Asian economies changing? A random sample
Borrowing money may be necessary for business expansion. However, too much borrowed money can also mean trouble. Are developing countries tending to borrow more? A random sample of 20 developing
A high school science teacher decided to give a series of lectures on current events. To determine if the lectures had any effect on student awareness of current events, an exam was given to the
With an ever-increasing world population, grain yields are extremely important. A random sample of 16 large grain producing regions in the world gave the following information about grain production
To compare two elementary schools regarding teaching of reading skills, 12 sets of identical twins were used. In each case, one child was selected at random and sent to school A, and his or her twin
How do the average weekly incomes of electricians and carpenters compare? A random sample of 17 regions in the United States gave the following information about average weekly income (in
One program to help people stop smoking cigarettes uses the method of posthypnotic suggestion to remind subjects to avoid smoking. A random sample of 18 subjects agreed to test the program. All
This cumulative review problem uses material from Chapters 3, 5, and 10. Recall that the Poisson distribution deals with rare events. Death from the kick of a horse is a rare event, even in the
Random samples of two species of iris gave the following petal lengths (in cm).(a) Use a 5% level of significance to test the claim that the population standard deviation of x1 is larger than
The following data are paired by date. Let x and y be random variables representing wind direction at 5 A.M. and 5 P.M., respectively (units are degrees on a compass, with 0° representing true
Commercial apple trees usually consist of two parts grafted together. The upper part, or graft, determines the character of the fruit, while the root stock determines the size of the tree. The
Showing 77100 - 77200
of 82267
First
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
Last