- Suppose the teacher in question 9 is teaching four algebra classes. She would like to predict the average course grade of all her students from only the midterm scores. Should she use inferential or
- Suppose the teacher in question 10 would like to predict the average grade of all her students by using only the midterm scores from one class. Should she use inferential or descriptive statistics?
- Suppose that in question 20, Weight Watchers uses a sample. Does this represent the use of inferential or descriptive statistics? How would your answer change if Weight Watchers used the population?
- Are the statistics you found in answering question 26 inferential or descriptive statistics?
- Use the data from question 10 to construct a relative frequency graph and a cumulative relative frequency graph for both EPS and DPS.Question 10Use the EPS and DPS data given in Table 2.3 in Chap. 2
- Use the data of question 21 to calculate(a) Coefficient of skewness(b) Pearson coefficient
- The daily rate of return for a stock (adjusted to an annual rate) is summarized in the following table. Can you show that these data do not come from a normal distribution? The mean is 0%and the
- Suppose you estimate a regression of y against x and find that b = 1.3 and σb = .4 (population standard error of the regression, which is known).(a) Construct a 90 % and a 99 % confidence interval
- Suppose the analyst of question 34 decides on the following regression:(a) Estimate the intercept and slope coefficients.(b) Use an F-test to test the joint significance of the slope coefficients.(c)
- Use the following information to answer question. It is believed that American League pitchers should have higher earned-run averages because of the designated hitter rule. A baseball analyst
- Use the following information to answer question. You are given the following return information for 3-month T-bills, the NYSE Index, Chrysler, Ford, and GM for the 3-year period from January 1985
- Use the data given in question 34 to compute the change in real wages between 1986 and 1990. Are workers any better off?Question 34Suppose you are given the following information about wages and
- The Students for an Affordable Education have asked you to estimate the average amount of money spent per semester on textbooks. To produce this estimate, you have decided to randomly sample 25
- A local deli prepares fresh potato salad for its customers every day. The unsold salad has to be thrown away. The demand for potato salad can be classified as low (100 lb), medium (200 lb), or high
- A hospital collects data on the number of emergency room patients in during a certain period. It is estimated that in an hour, the average number of emergency room patients to arrive is 1.2. If the
- A real estate agent in Connecticut is interested in the mean home price in the state. A random sample of 50 homes shows a mean home price of $175,622 and a sample standard deviation of $37,221.
- An auditor randomly samples 75 accounts receivable of a company and finds a sample mean of $128 with a sample standard deviation of $27. Construct a 90 % confidence interval for the mean accounts
- A random sample of 300 residents of a town shows that 55 % believe the mayor is doing a good job. Construct a 95 % confidence interval for the proportion of all residents who believe the mayor is
- An auditor randomly samples 50 accounts payable of a company and finds a sample mean of $1,100 with a sample standard deviation of $287. Construct a 90 % confidence interval for the mean accounts
- A random sample of 250 residents of a town shows that 55% favor a bond issue to finance new school construction. Construct a 99 % confidence interval for the proportion of all residents who favor the
- A random sample of 500 students at Average College finds the sample mean combined-SAT score to be 1.050 with a standard deviation of 120. Construct a 90 % confidence interval for the mean SAT score.
- Use the information given in question 25 to test H0: μ = 100 versus H1: μ ≠ 100 at the .01 level of significance.Question 25You are given the information X̅ = 150, σ = 30, and n = 20. Conduct
- You are given the information X̅ = 1,050, sx = 250, and n = 20. Conduct the following hypothesis test at the .10 level of significance:H0: μ = 1,100 versus H1: μ < 1,100 at the .10 level of
- A sample of 100 students in a high school has a sample mean score of 550 on the math portion of the SAT. Assuming that the sample standard deviation is 75, test, at the .05 level of significance, the
- Redo question 29, testing H0: μ = 500 against H1: μ > 500.Question 29A sample of 100 students in a high school has a sample mean score of 550 on the math portion of the SAT. Assuming that the
- A sample of 20 students in a high school has a sample mean score of 520 on the English portion of the SAT. If the sample standard deviation is 65, test, at the .01 level of significance, the
- Redo question 31, substituting the alternative hypothesis H1: μ > 500.Question 31A sample of 20 students in a high school has a sample mean score of 520 on the English portion of the SAT. If the
- Suppose a random sample of 25 people at a local weight-loss center is taken and the mean weight loss is found to be 12 lb. From past history, the standard deviation is known to be 3 lb. Test the
- Redo question 33, but assume that the standard deviation is not known and that 3 lb represents the sample standard deviation. Do the test at the 5 % level of significance.Question 33Suppose a random
- A quality control engineer is interested in testing the mean life of a new brand of light bulbs. A sample of 100 light bulbs is taken, and the sample mean life of these light bulbs is found to be
- Suppose that the quality control engineer in question 35 does not know what the standard deviation is and therefore uses the sample standard deviation. Does your answer to question 35 change? Why or
- Suppose that the quality control engineer in question 35 does not know what the standard deviation is and that this time, he selects a random sample of only 25 light bulbs. Does your answer to
- An auditor is interested in the mean value of a company’s accounts receivable.He randomly samples 200 accounts receivable and finds that the mean accounts receivable is $231. From past experience,
- Use the information given in question 38 to test the hypothesis that the population mean accounts receivable is greater than $200 at the .05 level of significance.Question 38An auditor is interested
- An investment advisor is interested in determining whether a retirement community represents a potential clientele base. Of the 2,000 residents, he randomly samples 100 individuals and finds their
- An automobile manufacturer claims that a new car gets an average of 35 miles per gallon. Assume that the distribution is known to be normal with a standard deviation of 3.2 miles per gallon. A random
- Use the information given in question 41, except this time assume that the standard deviation is not known and that 3.2 miles per gallon represents the sample standard deviation. Again test, at the
- An aspirin manufacturer claims that its aspirin stops headaches in less than 30 min. A random sample of 100 people who use the pain killer finds that the average time it takes to stop a headache is
- Bob’s SAT preparation service claims that the course it offers enables students to score an average of 600 or better on the math portion of the SAT. Suppose a random sample of 25 people taking the
- An advertising company claims that 80 % of stores that use their advertisements show increased sales. A random sample of 100 stores that used the company’s advertisements reveals that 80 showed
- Flip a coin 40 times and count the number of heads. Test, at the 5 % level of significance, whether the proportion of heads is .5.
- A manufacturer claims that 95 % of its parts are free of defects. A random sample of 100 parts finds that 92 are free of defects. Test the manufacturer’s claim at the 1 % level of significance.
- An investment advisor claims that 70 % of the stocks she recommends will increase in price. Suppose testing a random sample of 125 stocks she recommends reveals that 75 have increased in price. Test
- Ed’s bar exam review claims that 90% of the people who take its review course pass the bar exam on the first try. A random sample of 500 people who took the course reveals that 425 passed the bar
- Use the information given in question 49 to test, at the 1%level of significance, the null hypothesis that less than 80 % of those who take the course pass the bar exam on the first try.Question
- A popular commercial states that 4 out of 5 dentists who chew gum prefer sugarless gum. Suppose a random sample of 100 gum-chewing dentists is taken and 75 are found to prefer sugarless gum. Test, at
- A diet center claims that people subscribing to its program lose an average of 4 lb in the first week of the diet. Suppose 25 people in the diet center’s program are chosen at random and are found
- Use the information given in question 53 and test, at the 5 % level of significance, the alternative hypothesis that the mean weight loss is at least 4 lb.Question 53A diet center claims that people
- Suppose a farmer is interested in testing two fertilizers to see which is more effective. He uses the two fertilizers and gets the following results.Test, at the 10 % level of significance, the
- Use the following information to answer question. An investor recorded the performance of stock mutual funds during the last 3 years. He classified the stock mutual funds into three categories,
- Use the following information to answer question. An investor recorded the performance of stock mutual funds during the last 3 years. He classified the stock mutual funds into three categories,
- Use the following information to answer question. An investor recorded the performance of stock mutual funds during the last 3 years. He classified the stock mutual funds into three categories,
- A researcher contacted 1,000 doctors and asked them what kind of pain reliever they would like to have with them if they were stranded on a desert island. The responses wereDo a test to determine
- Professor Maloy uses different textbooks to teach statistics to two different college classes. Book 1 is the standard textbook also used by other instructors.Book 2 is a more recently introduced
- An insurance company reviewed its policyholders’ records during last year and organized the data in the following table. Do the data dictate rejection of the null hypothesis that the accident
- The number of patients to arrive at an emergency room each day is recorded in the accompanying table. The average number of emergency room patients is approximately 10. Do the data support the
- An eight o’clock train that pulls into Penn Station in New York City every weekday has a 20 % chance of being late. A supervisor from the Port Authority recorded the number of days that the train
- A nationwide testing service collected scores from a set of examination questions that were used during the last 3 years. The distribution is summarized in the accompanying table. The mean is 600 and
- The highway bureau records the following numbers of accidents during the past 365 days. Does this frequency distribution cause us to reject the null hypothesis that the accidents exhibit a Poisson
- Answer question 31 again, assuming that the sample is taken with replacement.Question 31The mean interest rate of 500 money market mutual funds is 7.98 % with astandard deviation of 1.01 %. Suppose
- Answer question 45 again, assuming that the sample is taken from a populationof four numbers, 1, 2, 3, and 4.Question 45Consider a population of six numbers, 1, 2, 3, 4, 5, and 6. What is the mean of
- Answer question 45 again, assuming that the sample is taken from a populationof three numbers, 1, 2, and 3.Question 45Consider a population of six numbers, 1, 2, 3, 4, 5, and 6. What is the mean of
- A production manager is interested in the number of defects in batches derived from different production processes. He examines a random sample drawn from each process and records the following
- Refer to question 41 to find the power of a 10 % level test when the true population mean mileage is 36 miles per gallon.Question 41An automobile manufacturer claims that a new car gets an average of
- Referring to question 43, find the power of a 5 % level test when the true population mean time for headache relief is 35 min.Question 43An aspirin manufacturer claims that its aspirin stops
- Assume that you’re taking a part-time job in a zoo. You are called upon to inspect a new cage built to contain a ferocious lion. Do you set up the null hypothesis that the cage is safe or that the
- What is the consequence of a Type I error in this question?Use the following information to answer question. A college professor gives a test that has 10 true–false questions. Two students take the
- What is the chance of student A getting exactly 6 correct answers when the null hypothesis is true?Use the following information to answer question. A college professor gives a test that has 10
- If the professor decides to reject the null hypothesis (that means passing the student) when the students get eight or more correct answers, what is the probability of a Type I error?Use the
- If the professor wants to raise the standard for passing the test to nine or more correct answers, what is the probability of a Type I error?Use the following information to answer question. A
- Student B studies one night before the test, so he knows about 60 % of the material. What is the probability that this student can pass the test when the standard for passing is eight correct
- Plot the OC curve, assuming p = .5, .6, .7, .8, .9, 1.Use the following information to answer question. A college professor gives a test that has 10 true–false questions. Two students take the
- Plot the power curve, assuming p = .5, .6, .7, .8, .9, 1.Use the following information to answer question. A college professor gives a test that has 10 true–false questions. Two students take the
- A poll was done to predict the outcome of the upcoming election. Of the 900 potential voters who responded, 500 plan to vote for the incumbent. If a candidate needs 50 % of the votes to win the
- On a given trading day, a financial economist randomly examines the stock prices of 500 companies and discovers that 205 went up and 295 went down.On this evidence, can he argue that more than 50 %
- The head of the accounting department randomly examined some accounting entries and was upset with the high proportion of incorrect invoices. He instituted a new system to keep the proportion of bad
- You are working for a consumer rights organization. You are interested in knowing whether the milk contained in 16-oz (1-pint) bottles really weighs 16 oz. You do not want to accuse the packer of
- You are working for a VCR manufacturer. There are three shifts in the plant: morning shift, evening shift, and midnight shift. The manager suspects that the midnight shift’s productivity is lower
- A college wants to increase its dormitory facilities to house 60 % of the students enrolled. In order to make sure that more than 60 % of the students want to live in the dormitory, the school
- A cola company wants to change its formula for producing cola, but first it wants to make sure that more than 70 % of its customers will like the new cola better than the old. Two thousand people
- In order to control the job turnover ratio, the personnel department did a survey and found that out of the 500 employees who were hired in the last year, only 234 stayed. Does that provide enough
- An insurance company wants to study the chances that a teenaged driver who owns a sports car will have an auto accident. Two thousand teenaged policyholders who own sports cars were sampled in the
- A food company claims that its new product, low-fat yogurt, is 99 % fat-free. The management wants to keep the proportion of bad (not 99 % fat-free) products below 2 %. Inspectors check 500 cups of
- A questionnaire was sent to 500 of a dry cleaner’s customers to solicit their opinions about service received. Twenty-three customers were found to be unhappy with the service. On this evidence,
- The dean of the school of business wants the proportion of A grades given out by his faculty members to be around 10 %. He randomly surveys 2,000 students in 50 classes and finds that of the 2,000
- The placement office in a college wants to know whether experience with personal computers is important in obtaining a job. The placement director randomly selects 600 job openings and finds that 313
- The head accountant in a large corporation conducted a survey last year to study the proportion of incorrect invoices. Of the 2,000 invoices sampled, 25 were incorrect. To lower the proportion, he
- A new medicine was invented to treat hay fever, but the new drug was found to have unpleasant side effects. An experiment on 5,000 women and 4,000 men showed that 100 women and 60 men suffered side
- Wood et al. (1979) studied the impact of comprehensive planning on the financial performance of banks. They used 4 random samples to perform their study. The sample size n, average annual percent
- A company believed its new toothpaste to have an effect in controlling tooth decay among children. It randomly selected a group of 400 children and gave them the new toothpaste. Another 300 children
- The PPP cola company wants to determine what age groups like its product. It surveyed 500 teenagers and 600 middle-aged people and found that 300 teenagers and 350 middle-aged people liked PPP cola.
- Use the data in the table to answer the following questions by using MINITAB.Current ratios for GM and Ford(a) Test whether the current ratio is equal to 1 for both GM and Ford, respectively, at α =
- Professor Preston et al. (1978) studied the effectiveness of bank premiums (stoneware, calculators) given as an inducement to open bank accounts. They randomly selected a sample of 200 accounts each
- The result of a random sample of before and after weights of 11 participants in a weight-loss program is shown in the table to the right. Using MINITAB, test whether the average weight loss is at
- A manager claims that the standard deviation in their mean delivery time is less than 2.5 days. A sample of 25 customers is taken. The average delivery time in the sample was 4 days with a standard
- Refer to Table 10.3, in which the sizes of U-bolts by taking samples of 5 every hour over three shifts from a population with mean μ and standard deviation σ .In Table 10.3, the means of the 24
- General Motors, the largest auto producer in this country, produces and sells its cars under five different brand names. Some of the cars sold under different names can be considered “sister
- Market analysts want to investigate the popularity of three types of radio programs. Their market research yielded the following ratings over the last 5 months. Can the analysts conclude that the
- In question 15, the market analyst hired a statistician to do the research. The statistician, realizing that these programs are broadcast at five different times of day, took the time factor into