The head of institutional research at a university believes that the mean age of full-time students is declining. In 1995, the mean age of a full-time student was known to be 27.4 years. After looking at the enrollment records of all 4934 full-time students in the current semester, he found that the mean age was 27.1 years, with a standard deviation of 7.3 years. He conducted a hypothesis of / years versus /years and obtained a P-value of 0.0019. He concluded that the mean age of full-time students did decline. Is there anything wrong with his research?
> x1 = 28, n1 = 254, x2 = 36, n2 = 301, 95% confidence
> x1 = 109, n1 = 475, x2 = 78, n2 = 325, 99% confidence
> x1 = 368, n1 = 541, x2 = 421, n2 = 593, 90% confidence
> Test whether / /
> Test whether / /
> Test whether / /
> Test whether / /
> A psychologist wants to know whether subjects respond faster to a go/no go stimulus or a choice stimulus. With the go/no go stimulus, subjects must respond to a particular stimulus by pressing a button and disregard other stimuli. In the choice stimulus,
> An educator wants to determine whether a new curriculum significantly improves standardized test scores for third grade students. She randomly divides 80 third-graders into two groups. Group 1 is taught using the new curriculum, while group 2 is taught u
> A political scientist wants to know how a random sample of 18- to 25-year-olds feel about Democrats and Republicans in Congress. She obtains a random sample of 1030 registered voters 18 to 25 years of age and asks, “Do you have favorable/ unfavorable [ro
> 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 40%. She wishes to obtain a sample of 300 respondents, so she e-mails the survey to 1500 randomly sel
> The Gallup Organization asked 1050 randomly selected adult Americans age 18 or older who consider themselves to be religious, “Do you believe it is morally acceptable or morally wrong [rotated] to conduct medical research using stem cells obtained fr
> A simple random sample of size n = 200 individuals with a valid driver’s license is asked if they drive an American-made automobile. Of the 200 individuals surveyed, 115 responded that they drive an American-made automobile. Determine if a majority of th
> A simple random sample of size n = 19 is drawn from a population that is normally distributed. The sample mean is found to be 0.8, and the sample standard deviation is found to be 0.4. Test whether the population mean is less than 1.0 at the = 0.01 lev
> Researchers measured regular testosterone levels in a random sample of athletes and then measured testosterone levels prior to an athletic event. They wanted to know whether testosterone levels increase prior to athletic events.
> In 2014, of the 37 million borrowers who have outstanding student loan balances, 14% have at least one past due student loan account. A researcher with the United States Department of Education believes this proportion has increased since then. Sourc
> According to the Pew Research Center, 55% of adult Americans support the death penalty for those convicted of murder. A social scientist wondered whether a higher proportion of adult Americans with at least a bachelor’s degree support the death penalty f
> An official with the Internal Revenue Service wished to estimate the proportion of high-income (greater than $100,000 annually) earners who under-reported their net income (and, therefore, their tax liability).
> A researcher wanted to estimate the average length of time mothers who gave birth via Caesarean section spent in a hospital after delivery of the baby.
> An investigator with the Food and Drug Administration wanted to determine whether a typical bag of potato chips contained less than the 16 ounces claimed by the manufacturer.
> Suppose you wish to determine if the mean IQ of students on your campus is different from the mean IQ in the general population, 100. To conduct this study, you obtain a simple random sample of 50 students on your campus, administer an IQ test, and recor
> To determine the public’s opinion of the police department, the police chief obtains a cluster sample of 15 census tracts within his jurisdiction and samples all households in the randomly selected tracts. Uniformed police officers go door to door to con
> A survey from the Gallup organization asked, “What do you think is the ideal number of children for a family to have?” Go to www.pearsonhighered.com/sullivanstats to obtain the data file 10_4_18 using the file format of your choice for the version of the
> According to Crestmont Research, the stock market has been up in 53.7% of all trading days over the past 50 years. A stock is up if the price per share increases in value day-over-day. An investor wondered whether the proportion of days Amazon stock was
> Suppose the mean wait-time for a telephone reservation agent at a large airline is 43 seconds. A manager with the airline is concerned that business may be lost due to customers having to wait too long for an agent. To address this concern, the manager d
> Politicians often form their positions on various policies through polling. Suppose the U.S. Congress is considering passage of a tax increase to pay down the national debt and national polls suggest the general population is equally split on the matter.
> Student loan debt has reached record levels in the United States. In a random sample of 100 individuals who have student loan debt, it was found the mean debt was $23,979 with a standard deviation of $31,400. Data based on results from the Federal Reserv
> According to the research firm Toluna, the proportion of individuals who text while driving is 0.26. Suppose a random sample of 60 individuals are asked to disclose if they text while driving. Results of the survey are shown next, where 0 indicates no an
> According to the National Sleep Foundation, children between the ages of 6 and 11 years should get 10 hours of sleep each night. In a survey of 56 parents of 6 to 11 year olds, it was found that the mean number of hours the children slept was 8.9 with a
> The Environmental Protection Agency (EPA) states that a 2013 Kia Optima should get 28 miles per gallon, on average. The website www.fueleconomy.gov allows users to report the miles per gallon that they get on their vehicle. Treat the following data as a
> According to the Federal Reserve Bank of Boston, among individuals who had credit cards in 2014, the mean number of cards was 3.5. Treat the individuals who have credit cards in the SullivanStatsSurveyI as a random sample of credit card holders. Go to ww
> Pass rates for Intermediate Algebra at a community college are 52.6%. In an effort to improve pass rates in the course, faculty of a community college develop a mastery- based learning model where course content is delivered in a lab through a computer p
> Suppose you are conducting a survey regarding illicit drug use among teenagers in the Baltimore school district. You obtain a cluster sample of 12 schools within the district and sample all sophomore students in the randomly selected schools. The survey
> In October 1945, the Gallup organization asked 1487 randomly sampled Americans, “Do you think we can develop a way to protect ourselves from atomic bombs in case other countries tried to use them against us?” with 788 responding yes. Did a majority of Am
> A psychologist obtains a random sample of 20 mothers in the first trimester of their pregnancy. The mothers are asked to play Mozart in the house at least 30 minutes each day until they give birth. After 5 years, the child is administered an IQ test. We
> A simple random sample of size n = 320 adults was asked their favorite ice cream flavor. Of the 320 individuals surveyed, 58 responded that they preferred mint chocolate chip. Do less than 25% of adults prefer mint chocolate chip ice cream? Use the = 0
> A simple random sample of size n = 40 is drawn from a population. The sample mean is found to be 108.5, and the sample standard deviation is found to be 17.9. Is the population mean greater than 100 at the = 0.05 level of significance?
> A simple random sample of size n = 65 is drawn from a population. The sample mean is found to be 583.1, and the sample standard deviation is found to be 114.9. Is the population mean different from 600 at the = 0.1 level of significance?
> A simple random sample of size n = 15 is drawn from a population that is normally distributed. The sample mean is found to be 23.8, and the sample standard deviation is found to be 6.3. Is the population mean different from 25 at the = 0.01 level of si
> To test /a simple random sample of size n = 23 is obtained from a population that is known to be normally distributed. (a) If / = 104.8 and s = 9.2, compute the test statistic. (b) If the researcher decides to test this hypothesis at the = 0.01 level o
> To test /, a simple random sample of size n = 25 is obtained from a population that is known to be normally distributed. (a) If / = 42.3 and s = 4.3, compute the test statistic. (b) If the researcher decides to test this hypothesis at the = 0.1 level o
> To test /a simple random sample of size n = 24 is obtained from a population that is known to be normally distributed. (a) If / = 47.1 and s = 10.3, compute the test statistic. (b) If the researcher decides to test this hypothesis at the = 0.05 level o
> (a) Determine the critical value for a right-tailed test of a population mean at the = 0.1 level of significance with 22 degrees of freedom. (b) Determine the critical value for a left-tailed test of a population mean at the = 0.01 level of significa
> A textbook publisher wants to determine what percentage of college professors either require or recommend that their students purchase textbook packages with supplemental materials. The publisher sends surveys by e-mail to a random sample of 320 faculty
> Phone number
> (a) Determine the critical value for a right-tailed test of a population mean at the = 0.01 level of significance with 15 degrees of freedom. (b) Determine the critical value for a left-tailed test of a population mean at the = 0.05 level of signific
> The life expectancy of a male during the course of the past 100 years is approximately 27,725 days. Go to Wikipedia.com and download the data that represent the life span of chief justices of Canada for those who have died. Conduct a test to determine wh
> Explain the difference between statistical significance and practical significance.
> The procedures for testing a hypothesis regarding a population mean are robust. What does this mean?
> It is well-documented that watching TV, working on a computer, or any other activity involving artificial light can be harmful to sleep patterns. Researchers wanted to determine if the artificial light from e-Readers also disrupted sleep. In the study, 1
> The exponential probability distribution can be used to model waiting time in line or the lifetime of electronic components. Its density function is skewed right. Suppose the wait time in a line can be modeled by the exponential distribution with = =
> Simulate drawing 100 simple random samples of size n = 15 from a population that is normally distributed with mean 100 and standard deviation 15. (a) Test the null hypothesis /for each of the 100 simple random samples. (b) If we test this hypothesis at t
> The mean IQ score of humans is 100. Suppose the director of Institutional Research at Joliet Junior College (JJC) obtains a simple random sample of 40 JJC students and finds the mean IQ is 103.4 with a standard deviation of 13.2. (a) Consider the hypothe
> The data set “Tornadoes_2017” located at www.pearsonhighered.com/sullivanstats contains a variety of variables that were measured for all tornadoes in the United States in 2017. (a) Compute the population mean length of a tornado in the United States in
> A magazine is conducting a study on the effects of infidelity in a marriage. The editors randomly select 400 women whose husbands were unfaithful and ask, “Do you believe a marriage can survive when the husband destroys the trust that must exist between
> The manufacturer of a daily dietary supplement claims that its product will help people lose weight. The company obtains a random sample of 950 adult males aged 20 to 74 who take the supplement and finds their mean weight loss after 8 weeks to be 0.9 pou
> A math teacher claims that she has developed a review course that increases the scores of students on the math portion of the SAT exam. Based on data from the College Board, SAT scores are normally distributed with = 515. The teacher obtains a random
> Problem 28
> Problem 27
> Problem 26
> Problem 25
> Go to www.pearsonhighered.com/sullivanstats to obtain the data file 10_3_28 using the file format of your choice for the version of the text you are using. The data represent the amount of time students in Sullivan’s online statistics course spent studyi
> The volume of a stock is the number of shares traded for a given day. In 2011, Starbucks stock had a mean daily volume of 7.52 million shares according to Yahoo!Finance. A random sample of 40 trading days in 2018 was obtained and the volume of shares tra
> A certain brand of apple juice is supposed to have 64 ounces of juice. Because the penalty for underfilling bottles is severe, the target mean amount of juice is 64.05 ounces. However, the filling machine is not precise, and the exact amount of jui
> Calcium is essential to tree growth. In 1990, the concentration of calcium in precipitation in Chautauqua, New York, was 0.11 milligram per liter /. A random sample of 10 precipitation dates in 2018 results in the following data: A normal probability plo
> A health teacher wants to research the weight of college students. She obtains the weights for all the students in her 9 A.M. class by looking at their driver’s licenses or state IDs.
> Among all Major League Baseball players, the mean speed of a four-seam fastball is 93.58 miles per hour (mph). The following data represent a random sample of four-seam fastballs thrown by David Price. (a) Draw a boxplot of the data. Does the boxplot sug
> Coors Field is home to the Colorado Rockies baseball team and is located in Denver, Colorado. Denver is approximately one mile above sea level, and the air there is “thinner.” Therefore, baseballs are thought to travel farther in this stadium. Does the e
> Michael Sullivan, son of the author, decided to enroll in a reading course that allegedly increases reading speed and comprehension. Prior to enrolling in the class, Michael read 198 words per minute (wpm). The following data represent the words per minu
> The mean waiting time at the drive-thru of a fast-food restaurant from the time an order is placed to the time the order is received is 84.3 seconds. A manager devises a new drive-thru system that he believes will decrease wait time. He initiates the new
> In 2001, the mean household expenditure for energy was $1493, according to data from the U.S. Energy Information Administration. An economist wanted to know whether this amount has changed significantly from its 2001 level. In a random sample of 35
> In 2002, the mean age of an inmate on death row was 40.7 years, according to data from the U.S. Department of Justice. A sociologist wondered whether the mean age of a death-row inmate has changed since then. She randomly selects 32 death-row inmates and
> According to the American Time Use Survey, the typical American spends 154.8 minutes (2.58 hours) per day watching television. A survey of 50 Internet users results in a mean time watching television per day of 128.7 minutes, with a standard deviation of
> A Fair Isaac Corporation (FICO) score is used by credit agencies (such as mortgage companies and banks) to assess the creditworthiness of individuals. Values range from 300 to 850, with a FICO score over 700 considered to be a quality credit risk. Accord
> Para-nonylphenol is found in polyvinyl chloride (PVC) used in the food processing and packaging industries. Researchers wanted to determine the effect this substance had on the organ weight of first-generation mice when both parents were exposed to 5
> In a study published in the American Journal of Psychiatry (157:737–744, May 2000), researchers wanted to measure the effect of alcohol on the hippocampal region, the portion of the brain responsible for long-term memory storage, in adolescents. The rese
> A newspaper article reported, “The Cosmopolitan magazine survey of more than 5000 Australian women aged 18–34 found about 42 percent considered themselves overweight or obese.” Source: Herald Sun, September 9, 2007.
> Do students who learned English and another language simultaneously score worse on the SAT Critical Reading exam than the general population of test takers? The mean score among all test takers on the SAT Critical Reading exam is 501. A random sample of
> The ACT is a college entrance exam. ACT has determined that a score of 22 on the mathematics portion of the ACT suggests that a student is ready for college-level mathematics. To achieve this goal, ACT recommends that students take a core curriculum of m
> In 1990, the mean height of women 20 years of age or older was 63.7 inches based on data obtained from the Centers for Disease Control and Prevention’s Advance Data Report, No. 347. Suppose that a random sample of 45 women who are 20 years of age or olde
> According to the Crown ATM Network, the mean ATM withdrawal is $67. PayEase, Inc., manufactures an ATM that allows one to pay bills (electric, water, parking tickets, and so on), as well as withdraw money. A review of 40 withdrawals shows the mean withdr
> To test /a simple random sample of size n = 40 is obtained. (a) Does the population have to be normally distributed to test this hypothesis by using the methods presented in this section? Why? (b) If / = 48.3 and s = 8.5, compute the test statistic. (c)
> To test / a simple random sample of size n = 35 is obtained. (a) Does the population have to be normally distributed to test this hypothesis by using the methods presented in this section? Why? (b) If / = 101.9 and s = 5.9, compute the test statistic. (c
> To test /a simple random sample of size n = 13 is obtained from a population that is known to be normally distributed. (a) If / = 4.9 and s = 1.3, compute the test statistic. (b) Draw a t-distribution with the area that represents the P-value shaded. (c)
> To test / a simple random sample of size n = 18 is obtained from a population that is known to be normally distributed. (a) If / = 18.3 and s = 4.3, compute the test statistic. (b) Draw a t-distribution with the area that represents the P-value shaded. (
> To test /a simple random sample of size n = 22 is obtained from a population that is known to be normally distributed. (a) If /= 76.9 and s = 8.5, compute the test statistic. (b) If the researcher decides to test this hypothesis at the = 0.02 level of
> True or False: When testing a hypothesis using the Classical Approach, if the sample proportion is too many standard deviations from the proportion stated in the null hypothesis, we reject the null hypothesis.
> Cold Stone Creamery is considering opening a new store in O’Fallon. Before opening, the company wants to know the percentage of households in O’Fallon that regularly visit an ice cream shop. The market researcher obtains a list of households in O’Fallon,
> When observed results are unlikely under the assumption that the null hypothesis is true, we say the result is_____ and we reject the null hypothesis.
> Explain what “statistical significance” means.
> The headline reporting the results of a poll conducted by the Gallup organization stated “Majority of Americans at Personal Best in the Morning.” The results indicated that a survey of 1100 Americans resulted in 55% stating they were at their personal be
> Discuss the advantages and disadvantages of using the Classical Approach to hypothesis testing. Discuss the advantages and disadvantages of using the P-value approach to hypothesis testing.
> Suppose we are testing the hypothesis / versus / and we find the P-value to be 0.02. Explain what this means. Would you reject the null hypothesis? Why?
> Suppose we are testing the hypothesis / versus / and we find the P-value to be 0.23. Explain what this means. Would you reject the null hypothesis? Why?
> Explain what a P-value is. What is the criterion for rejecting the null hypothesis using the P-value approach?
> Yale University graduate student J. Kiley Hamlin conducted an experiment in which 16 ten-month-old babies were asked to watch a climber character attempt to ascend a hill. On two occasions, the baby witnesses the character fail to make the climb. On the
> Based on historical birthing records, the proportion of males born worldwide is 0.51. In other words, the commonly held belief that boys are just as likely as girls is false. Systematic lupus erythematosus (SLE), or lupus for short, is a disease i
> Parapsychology (psi) is a field of study that deals with clairvoyance or precognition. Psi made its way back into the news when a professional, refereed journal published an article by Cornell psychologist Daryl Bem, in which he claimed to demonstrate th
> A polling organization conducts a study to estimate the percentage of households that speaks a foreign language as the primary language. It mails a questionnaire to 1023 randomly selected households throughout the United States and asks the head of house
> Simulate drawing 100 simple random samples of size n = 40 from a population whose proportion is 0.3. (a) Test the null hypothesis / each simulated sample. (b) If we test the hypothesis at the a = 0.1 level of significance, how many of the 100 samples wou
