New Semester
Started
Get
50% OFF
Study Help!
--h --m --s
Claim Now
Question Answers
Textbooks
Find textbooks, questions and answers
Oops, something went wrong!
Change your search query and then try again
S
Books
FREE
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
Tutors
Online Tutors
Find a Tutor
Hire a Tutor
Become a Tutor
AI Tutor
AI Study Planner
NEW
Sell Books
Search
Search
Sign In
Register
study help
business
business statistics in practice
The Practice Of Statistics 5th Edition Daren S. Starnes, Josh Tabor - Solutions
Earthquake intensities are measured using a device called a seismograph, which is designed to be most sensitive to earthquakes with intensities between 4.0 and 9.0 on the Richter scale. Measurements of nine earthquakes gave the following readings:4.5 L 5.5 H 8.7 8.9 6.0 H 5.2 where L indicates that
The percentage of students with less than $10 in their possession is closest to(a) 30%. (b) 35%. (c) 45%. (d) 60%. (e) 70%.In a statistics class with 136 students, the professor records how much money (in dollars) each student has in his or her possession during the first class of the semester. The
Which of the following statements about this distribution is not correct?(a) The histogram is right-skewed.(b) The median is less than $20.(c) The IQR is $35.(d) The mean is greater than the median.(e) The histogram is unimodal.In a statistics class with 136 students, the professor records how much
Forty students took a statistics examination having a maximum of 50 points. The score distribution is given in the following stem-and-leaf plot:0 28 1 2245 2 01333358889 3 001356679 4 22444466788 5 000 The third quartile of the score distribution is equal to(a) 45. (b) 44. (c) 43. (d) 32. (e) 23.In
The mean salary of all female workers is $35,000. The mean salary of all male workers is $41,000. What must be true about the mean salary of all workers?(a) It must be $38,000.(b) It must be larger than the median salary.(c) It could be any number between $35,000 and$41,000.(d) It must be larger
What percent of all small companies receiving questionnaires responded?(a) 12.5% (c) 33.3% (e) 62.5%(b) 20.8% (d) 50.8%A survey was designed to study how business operations vary according to their size. Companies were classified as small, medium, or large. Questionnaires were sent to 200 randomly
Which of the following conclusions seems to be supported by the data?(a) There are more small companies than large companies in the survey.(b) Small companies appear to have a higher response rate than medium or big companies.(c) Exactly the same number of companies responded as didn’t
An experiment was conducted to investigate the effect of a new weed killer to prevent weed growth in onion crops. Two chemicals were used: the standard weed killer (C) and the new chemical (W). Both chemicals were tested at high and low concentrations on a total of 50 test plots. The percent of
You are interested in how much time students spend on the Internet each day. Here are data on the time spent on the Internet (in minutes) for a particular day reported by a random sample of 30 students at a large high school:7 20 24 25 25 28 28 30 32 35 42 43 44 45 46 47 48 48 50 51 72 75 77 78 79
A study among the Pima Indians of Arizona investigated the relationship between a mother’s diabetic status and the appearance of birth defects in her children.The results appear in the two-way table below.Birth Defects Diabetic Status Nondiabetic Prediabetic Diabetic Total None 754 362 38 One or
The back-to-back stemplot shows the lifetimes of several Brand X and Brand Y batteries.1 1 7 2 2 2 6 3 3 4 223334 4 56889 5 0 5 Key: 4|2 represents 420–429 hours.Brand X Brand Y 2110 99775 3221 4 5 (a) What is the longest that any battery lasted?(b) Give a reason someone might prefer a Brand X
During the early part of the 1994 baseball season, many fans and players noticed that the number of home runs being hit seemed unusually large. Here are the data on the number of home runs hit by American League and National League teams in the early part of the 1994 season:American League: 35 40
State the null and alternative hypotheses for a significance test about a population parameter.
Interpret a P-value in context.
Determine whether the results of a study are statistically significant and make an appropriate conclusion using a significance level.
Interpret a Type I and a Type II error in context and give a consequence of each.
According to the Web site sleepdeprivation.com, 85% of teens are getting less than eight hours of sleep a night. Jannie wonders whether this result holds in her large high school. She asks an SRS of 100 students at the school how much sleep they get on a typical night. In all, 75 of the responders
As part of its 2010 census marketing campaign, the U.S. Census Bureau advertised“10 questions, 10 minutes—that’s all it takes.” On the census form itself, we read, “The U.S. Census Bureau estimates that, for the average household, this form will take about 10 minutes to complete,
Attitudes The Survey of Study Habits and Attitudes(SSHA) is a psychological test that measures students’attitudes toward school and study habits. Scores range from 0 to 200. The mean score for U.S. college students is about 115. A teacher suspects that older students have better attitudes toward
Anemia Hemoglobin is a protein in red blood cells that carries oxygen from the lungs to body tissues.People with less than 12 grams of hemoglobin per deciliter of blood (g/dl) are anemic. A public health official in Jordan suspects that Jordanian children are at risk of anemia. He measures a random
Lefties Simon reads a newspaper report claiming that 12% of all adults in the United States are lefthanded.He wonders if the proportion of lefties at his large community college is really 12%. Simon chooses an SRS of 100 students and records whether each student is right- or left-handed.
Don’t argue! A Gallup Poll report revealed that 72% of teens said they seldom or never argue with their friends.5 Yvonne wonders whether this result holds true in her large high school. So she surveys a random sample of 150 students at her school.
Cold cabin? During the winter months, the temperatures at the Colorado cabin owned by the Starnes family can stay well below freezing (32°F or 0°C) for weeks at a time. To prevent the pipes from freezing, Mrs. Starnes sets the thermostat at 50°F. The manufacturer claims that the thermostat
Ski jump When ski jumpers take off, the distance they fly varies considerably depending on their speed, skill, and wind conditions. Event organizers must position the landing area to allow for differences in the distances that the athletes fly. For a particular competition, the organizers estimate
Better parking A change is made that should improve student satisfaction with the parking situation at a local high school. Right now, 37% of students approve of the parking that’s provided. The null hypothesis H0 : p > 0.37 is tested against the alternative Ha : p = 0.37.
Better parking A change is made that should improve student satisfaction with the parking situation at your school. Right now, 37% of students approve of the parking that’s provided. The null hypothesis H0 : p^ = 0.37 is tested against the alternative Ha : p^ ≠ 0.37.
Birth weights In planning a study of the birth weights of babies whose mothers did not see a doctor before delivery, a researcher states the hypotheses as H0 : x– = 1000 grams Ha : x– < 1000 grams
Birth weights In planning a study of the birth weights of babies whose mothers did not see a doctor before delivery, a researcher states the hypotheses as H0 : m < 1000 grams Ha : m = 900 grams
Attitudes In the study of older students’ attitudes from Exercise 1, the sample mean SSHA score was 125.7 and the sample standard deviation was 29.8.A significance test yields a P-value of 0.0101.(a) Explain what it would mean for the null hypothesis to be true in this setting.(b) Interpret the
Anemia For the study of Jordanian children in Exercise 2, the sample mean hemoglobin level was 11.3 g/dl and the sample standard deviation was 1.6 g/dl. A significance test yields a P-value of 0.0016.(a) Explain what it would mean for the null hypothesis to be true in this setting.(b) Interpret the
Lefties Refer to Exercise 3. In Simon’s SRS, 16 of the students were left-handed. A significance test yields a P-value of 0.2184. What conclusion would you make if a = 0.10? If a = 0.05? Justify your answers.
Don’t argue! Refer to Exercise 4. For Yvonne’s survey, 96 students in the sample said they rarely or never argue with friends. A significance test yields a P-value of 0.0291. What conclusion would you make if a = 0.05? If a = 0.01? Justify your answers.
Attitudes Refer to Exercise 11. What conclusion would you make if a = 0.05? If a = 0.01? Justify your answers.
Anemia Refer to Exercise 12. What conclusion would you make if a = 0.05? If a = 0.01? Justify your answers.
Interpreting a P-value When asked to explain the meaning of the P-value in Exercise 13, a student says, “This means there is about a 22% chance that the null hypothesis is true.” Explain why the student’s explanation is wrong.
Interpreting a P-value When asked to explain the meaning of the P-value in Exercise 14, a student says,“There is a 0.0291 probability of getting a sample proportion of p^ = 96/150 = 0.64 by chance alone.”Explain why the student’s explanation is wrong.
Drawing conclusions A student performs a test of H0 : p = 0.75 versus Ha : p > 0.75 and gets a P-value of 0.99. The student writes: “Because the P-value is greater than 0.75, we reject H0. The data prove that Ha is true.” Explain what is wrong with this conclusion.
Drawing conclusions A student performs a test of H0: p = 0.5 versus Ha: p ≠ 0.5 and gets a P-value of 0.63. The student writes: “Because the P-value is greater than a = 0.05, we accept H0. The data provide convincing evidence that the null hypothesis is true.” Explain what is wrong with this
Awful accidents(a) State hypotheses for a significance test to determine whether the average response time has decreased. Be sure to define the parameter of interest.(b) Describe a Type I error and a Type II error in this setting, and explain the consequences of each.(c) Which is more serious in
Awful accidents(a) State hypotheses for a significance test to determine whether first responders are arriving within 8 minutes of the call more often. Be sure to define the parameter of interest.(b) Describe a Type I error and a Type II error in this setting and explain the consequences of
Opening a restaurant You are thinking about opening a restaurant and are searching for a good location.From research you have done, you know that the mean income of those living near the restaurant must be over $85,000 to support the type of upscale restaurant you wish to open. You decide to take a
Blood pressure screening Your company markets a computerized device for detecting high blood pressure. The device measures an individual’s blood pressure once per hour at a randomly selected time throughout a 12-hour period. Then it calculates the mean systolic (top number) pressure for the
Experiments on learning in animals sometimes measure how long it takes mice to find their way through a maze. The mean time is 18 seconds for one particular maze. A researcher thinks that a loud noise will cause the mice to complete the maze faster. She measures how long each of 10 mice takes with
A Type I error in the context of this study occurs if the city council (a) finds convincing evidence that a majority of residents supports the tax increase, when in reality there isn’t convincing evidence that a majority supports the increase.(b) finds convincing evidence that a majority of
In the sample, p^ = 158/300 = 0.527. The resulting P-value is 0.18. What is the correct interpretation of this P-value?(a) Only 18% of the city residents support the tax increase.(b) There is an 18% chance that the majority of residents supports the tax increase.(c) Assuming that 50% of residents
28. Based on the P-value in Exercise 27, which of the following would be the most appropriate conclusion?(a) Because the P-value is large, we reject H0. We have convincing evidence that more than 50% of city residents support the tax increase.(b) Because the P-value is large, we fail to reject H0.
Women in math (5.3) Of the 24,611 degrees in mathematics given by U.S. colleges and universities in a recent year, 70% were bachelor’s degrees, 24% were master’s degrees, and the rest were doctorates. Moreover, women earned 43% of the bachelor’s degrees, 41% of the master’s degrees, and 29%
Explaining confidence (8.2) Here is an explanation from a newspaper concerning one of its opinion polls. Explain what is wrong with the following statement.For a poll of 1,600 adults, the variation due to sampling error is no more than three percentage points either way. The error margin is said to
State and check the Random, 10%, and Large Counts conditions for performing a significance test about a population proportion.
Perform a significance test about a population proportion.
Interpret the power of a test and describe what factors affect the power of a test.
Describe the relationship among the probability of a Type I error (significance level), the probability of a Type II error, and the power of a test.
Home computers Jason reads a report that says 80% of U.S. high school students have a computer at home. He believes the proportion is smaller than 0.80 at his large rural high school. Jason chooses an SRS of 60 students and records whether they have a computer at home.
Walking to school A recent report claimed that 13%of students typically walk to school.10 DeAnna thinks that the proportion is higher than 0.13 at her large elementary school, so she surveys a random sample of 100 students to find out.
No test You toss a coin 10 times to perform a test of H0 : p = 0.5 that the coin is balanced against Ha : p ≠ 0.5.
No test A college president says, “99% of the alumni support my firing of Coach Boggs.” You contact an SRS of 200 of the college’s 15,000 living alumni to perform a test of H0 : p = 0.99 versus Ha : p < 0.99.
SRS, 41 of the students had a computer at home.(a) Calculate the test statistic.(b) Find the P-value using Table A or technology. Show this result as an area under a standard Normal curve.
Walking to school Refer to Exercise 32. For DeAnna’s survey, 17 students in the sample said they typically walk to school.(a) Calculate the test statistic.(b) Find the P-value using Table A or technology. Show this result as an area under a standard Normal curve.
Significance tests A test of H0 : p = 0.5 versus Ha : p > 0.5 has test statistic z = 2.19.(a) What conclusion would you draw at the 5% significance level? At the 1% level?(b) If the alternative hypothesis were Ha : p ≠ 0.5, what conclusion would you draw at the 5% significance level? At the 1%
Significance tests A test of H0 : p = 0.65 against Ha : p < 0.65 has test statistic z = –1.78.(a) What conclusion would you draw at the 5% significance level? At the 1% level?(b) If the alternative hypothesis were Ha : p ≠ 0.65, what conclusion would you draw at the 5% significance level? At
Better parking A local high school makes a change that should improve student satisfaction with the parking situation. Before the change, 37% of the school’s students approved of the parking that was provided. After the change, the principal surveys an SRS of 200 of the over 2500 students at the
Side effects A drug manufacturer claims that less than 10% of patients who take its new drug for treating Alzheimer’s disease will experience nausea. To test this claim, researchers conduct an experiment.They give the new drug to a random sample of 300 out of 5000 Alzheimer’s patients whose
Are boys more likely? We hear that newborn babies are more likely to be boys than girls. Is this true? A random sample of 25,468 firstborn children included 13,173 boys.11(a) Do these data give convincing evidence that firstborn children are more likely to be boys than girls?(b) To what population
Fresh coffee People of taste are supposed to prefer fresh-brewed coffee to the instant variety.On the other hand, perhaps many coffee drinkers just want their caffeine fix. A skeptic claims that only half of all coffee drinkers prefer fresh-brewed coffee. To test this claim, we ask a random sample
43. Bullies in middle school A University of Illinois study on aggressive behavior surveyed a random sample of 558 middle school students. When asked to describe their behavior in the last 30 days, 445 students said their behavior included physical aggression, social ridicule, teasing,
Is this coin fair? The French naturalist Count Buffon (1707–1788) tossed a coin 4040 times. He got 2048 heads. That’s a bit more than one-half.Is this evidence that Count Buffon’s coin was not balanced? To find out, Luisa decides to perform a significance test. Unfortunately, she made a few
Teen drivers A state’s Division of Motor Vehicles (DMV) claims that 60% of teens pass their driving test on the first attempt. An investigative reporter examines an SRS of the DMV records for 125 teens; 86 of them passed the test on their first try. Is there convincing evidence at the a = 0.05
We want to be rich In a recent year, 73% of firstyear college students responding to a national survey identified “being very well-off financially” as an important personal goal. A state university finds that 132 of an SRS of 200 of its first-year students say that this goal is important. Is
Teen drivers Refer to Exercise 45.(a) Construct and interpret a 95% confidence interval for the proportion of all teens in the state who passed their driving test on the first attempt.(b) Explain what the interval in part (a) tells you about the DMV’s claim.
We want to be rich Refer to Exercise 46.(a) Construct and interpret a 95% confidence interval for the true proportion p of all first-year students at the university who would identify being well-off as an important personal goal.(b) Explain what the interval in part (a) tells you about whether the
Do you Tweet? In early 2012, the Pew Internet and American Life Project asked a random sample of U.S. adults, “Do you ever . . . use Twitter or another service to share updates about yourself or to see updates about others?” According to Pew, the resulting 95% confidence interval is (0.123,
Losing weight A Gallup Poll found that 59% of the people in its sample said “Yes” when asked, “Would you like to lose weight?” Gallup announced: “For results based on the total sample of national adults, one can say with 95% confidence that the margin of (sampling) error is ±3 percentage
Teens and sex The Gallup Youth Survey asked a random sample of U.S. teens aged 13 to 17 whether they thought that young people should wait to have sex until marriage.15 The Minitab output below shows the results of a significance test and a 95%confidence interval based on the survey data.(a) Define
Reporting cheating What proportion of students are willing to report cheating by other students? A student project put this question to an SRS of 172 undergraduates at a large university: “You witness two students cheating on a quiz. Do you go to the professor?” The Minitab output below shows
Better parking Refer to Exercise 39.(a) Describe a Type I error and a Type II error in this setting, and explain the consequences of each.(b) The test has a power of 0.75 to detect that p = 0.45.Explain what this means.(c) Identify two ways to increase the power in part (b).
Side effects Refer to Exercise 40.(a) Describe a Type I error and a Type II error in this setting, and explain the consequences of each.(b) The test has a power of 0.54 to detect that p = 0.07.Explain what this means.(c) Identify two ways to increase the power in part (b).
Error probabilities You read that a statistical test at significance level a = 0.05 has power 0.78. What are the probabilities of Type I and Type II errors for this test?
Error probabilities You read that a statistical test at the a = 0.01 level has probability 0.14 of making a Type II error when a specific alternative is true.What is the power of the test against this alternative?
Power A drug manufacturer claims that fewer than 10% of patients who take its new drug for treating Alzheimer’s disease will experience nausea. To test this claim, a significance test is carried out of H0 : p = 0.10 Ha : p < 0.10 You learn that the power of this test at the 5% significance level
What is power? You manufacture and sell a liquid product whose electrical conductivity is supposed to be 5. You plan to make six measurements of the conductivity of each lot of product. If the product meets specifications, the mean of many measurements will be 5. You will therefore test H0 : m = 5
After once again losing a football game to the archrival, a college’s alumni association conducted a survey to see if alumni were in favor of firing the coach. An SRS of 100 alumni from the population of all living alumni was taken, and 64 of the alumni in the sample were in favor of firing the
Which of the following is not a condition for performing a significance test about a population proportion p?(a) The data should come from a random sample or randomized experiment.(b) Both np0 and n(1 – p0) should be at least 10.(c) If you are sampling without replacement from a finite
The z statistic for a test of H0 : p = 0.4 versus Ha : p ≠ 0.4 is z = 2.43. This test is (a) not significant at either a = 0.05 or a = 0.01.(b) significant at a = 0.05 but not at a = 0.01.(c) significant at a = 0.01 but not at a = 0.05.(d) significant at both a = 0.05 and a = 0.01.(e)
Which of the following 95% confidence intervals would lead us to reject H0 : p = 0.30 in favor of Ha : p ≠ 0.30 at the 5% significance level?(a) (0.19, 0.27) (c) (0.27, 0.31) (e) None of these(b) (0.24, 0.30) (d) (0.29, 0.38)
Packaging CDs (6.2, 5.3) A manufacturer of compact discs (CDs) wants to be sure that their CDs will fit inside the plastic cases they have bought for packaging. Both the CDs and the cases are circular. According to the supplier, the plastic cases vary Normally with mean diameter m = 4.2 inches and
Let X = the diameter of a randomly selected CD and Y = the diameter of a randomly selected case.Describe the shape, center, and spread of the distribution of the random variable X – Y. What is the importance of this random variable to the CD manufacturer?(b) Compute the probability that a
Cash to find work? (4.2) Will cash bonuses speed the return to work of unemployed people? The Illinois Department of Employment Security designed an experiment to find out. The subjects were 10,065 people aged 20 to 54 who were filing claims for unemployment insurance. Some were offered $500 if
State and check the Random, 10%, and Normal/Large Sample conditions for performing a significance test about a population mean.
Perform a significance test about a population mean.
Use a confidence interval to draw a conclusion for a two-sided test about a population parameter.
Perform a significance test about a mean difference using paired data.
Attitudes The Survey of Study Habits and Attitudes(SSHA) is a psychological test that measures students’ attitudes toward school and study habits.Scores range from 0 to 200. Higher scores indicate more positive attitudes. The mean score for U.S.college students is about 115. A teacher suspects
Anemia Hemoglobin is a protein in red blood cells that carries oxygen from the lungs to body tissues.People with fewer than 12 grams of hemoglobin per deciliter of blood (g/dl) are anemic. A public health official in Jordan suspects that Jordanian children are at risk of anemia. He measures a
Ancient air The composition of the earth’s atmosphere may have changed over time. To try to discover the nature of the atmosphere long ago, we can examine the gas in bubbles inside ancient amber. Amber is tree resin that has hardened and been trapped in rocks. The gas in bubbles within amber
4 65.0 64.4 63.3 54.8 64.5 60.8 49.1 51.0 Explain why we should not carry out a one-sample t test in this setting.
Paying high prices? A retailer entered into an exclusive agreement with a supplier who guaranteed to provide all products at competitive prices. The retailer eventually began to purchase supplies from other vendors who offered better prices. The original supplier filed a lawsuit claiming violation
Attitudes In the study of older students’ attitudes from Exercise 65, the sample mean SSHA score was 125.7 and the sample standard deviation was 29.8.(a) Calculate the test statistic.(b) Find the P-value using Table B. Then obtain a more precise P-value from your calculator.
Anemia For the study of Jordanian children in Exercise 66, the sample mean hemoglobin level was 11.3 mg/dl and the sample standard deviation was 1.6 mg/dl.(a) Calculate the test statistic.(b) Find the P-value using Table B. Then obtain a more precise P-value from your calculator.
One-sided test Suppose you carry out a significance test of H0 : m = 5 versus Ha : m < 5 based on a sample of size n = 20 and obtain t = −1.81.(a) Find the P-value for this test using Table B or technology.What conclusion would you draw at the 5%significance level? At the 1% significance
Two-sided test The one-sample t statistic from a sample of n = 25 observations for the two-sided test of H0 : m = 64 Ha : m ≠ 64 has the value t = −1.12.(a) Find the P-value for this test using Table B or technology.What conclusion would you draw at the 5%significance level? At the 1%
Showing 5100 - 5200
of 6217
First
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
Last
Step by Step Answers
Get 50% OFF
Claim Now
