Q&A Hero

Q: As the sample size increases, the variability among the sample means a. increases b. decreases c. remains the same d. depends upon the specific population being sampled

Q: As the sample size increases, the a. standard deviation of the population decreases b. population mean increases c. standard error of the mean decreases d. standard error of the mean increases

Q: A simple random sample of 64 observations was taken from a large population. The population standard deviation is 120. The sample mean was determined to be 320. The standard error of the mean is a. 1.875 b. 40 c. 5 d. 15

Q: From a population of 500 elements, a sample of 225 elements is selected. It is known that the variance of the population is 900. The standard error of the mean is approximately a. 1.1022 b. 2 c. 30 d. 1.4847

Q: From a population of 200 elements, the standard deviation is known to be 14. A sample of 49 elements is selected. It is determined that the sample mean is 56. The standard error of the mean is a. 3 b. 2 c. greater than 2 d. less than 2

Q: A finite population correction factor is needed in computing the standard deviation of the sampling distribution of sample means a. whenever the population is infinite b. whenever the sample size is more than 5% of the population size c. whenever the sample size is less than 5% of the population size d. The correction factor is not necessary if the population has a normal distribution.

Q: In computing the standard error of the mean, the finite population correction factor is notused when

Q: The standard deviation of all possible values is called the a. standard error of proportion b. standard error of the mean c. mean deviation d. central variation

Q: The expected value of the random variable isa. b. the standard errorc. the sample sized.

Q: Since the sample size is always smaller than the size of the population, the sample mean must a. always be smaller than the population mean b. be larger than the population mean c. be equal to the population mean d. None of the alternative ANSWERS is correct.

Q: The sampling distribution of the sample meana. is the probability distribution showing all possible values of the sample meanb. is used as a point estimator of the population mean c. is an unbiased estimatord. shows the distribution of all possible values of

Q: The probability distribution of all possible values of the sample mean is called the a. central probability distribution b. sampling distribution of the sample mean c. random variation d. standard error

Q: If we consider the simple random sampling process as an experiment, the sample mean is a. always zero b. always smaller than the population mean c. a random variable d. exactly equal to the population mean

Q: Refer to Exhibit 7-3. The point estimate of the population standard deviation is a. 2.000 b. 1.291 c. 1.414 d. 1.667

Q: Exhibit 7-3The following information was collected from a simple random sample of a population.161918172018a. 18.0b. 19.6c. 108d. sixteen, since 16 is the smallest value in the sample

Q: Refer to Exhibit 7-2. The point estimate of the proportion in the population who will respond "no" isa. 75b. 0.25c. 0.75d. 0.50

Q: Exhibit 7-2Four hundred registered voters were randomly selected asked whether gun laws should be changed. Three hundred said "yes," and one hundred said "no."Refer to Exhibit 7-2. The point estimate of the proportion in the population who will respond "yes" isa. 300b. approximately 300c. 0.75d. 0.25

Q: Refer to Exhibit 7-1. The mean of the populationa. is 14b. is 15c. is 15.1581d. could be any value

Q: Refer to Exhibit 7-1. The point estimate of the population standard deviation is a. 2.500 b. 1.581 c. 2.000 d. 1.414

Q: Exhibit 7-1The following data was collected from a simple random sample from a process (an infinite population).1315141612Refer to Exhibit 7-1. The point estimate of the population meana. is 5b. is 14c. is 4d. cannot be determined because the population is infinite

Q: A simple random sample of 28 observations was taken from a large population. The sample mean equaled 50. Fifty is aa. population parameterb. point estimatorc. sample parameterd. point estimate

Q: A probability distribution for all possible values of a sample statistic is known as a a. sample statistic b. parameter c. simple random sample d. sampling distribution

Q: The sampling error is the a. same as the standard error b. absolute value of the difference between an unbiased point estimate and the corresponding population parameter c. error caused by selecting a bad sample d. standard deviation multiplied by the sample size

Q: A simple random sample of 5 observations from a population containing 400 elements was taken, and the following values were obtained.1218192021A point estimate of the population mean isa. 5b. 18c. 19d. 20

Q: Which of the following is(are) point estimator(s)?a. b. c. sd. All of these answers are correct.

Q: The sample statistic sis the point estimator ofa. b.c. d.

Q: The sample mean is the point estimator ofa. b. c. d.

Q: In point estimation, data from the a. population is used to estimate the population parameter b. sample is used to estimate the population parameter c. sample is used to estimate the sample statistic d. None of the alternative ANSWERS is correct.

Q: A single numerical value used as an estimate of a population parameter is known as a. a parameter b. a population parameter c. both a parameter or a population parameter are correct d. a point estimate

Q: A sample statistic, such as , that estimates the value of the corresponding population parameter is known as a a. point estimator b. parameter c. population parameter d. Both a parameter and a population parameter are correct.

Q: A numerical measure from a sample, such as a sample mean, is known as a. a statistic b. a parameter c. the mean deviation d. the central limit theorem

Q: A numerical measure from a population, such as a population mean, is called a. a statistic b. a parameter c. a sample d. the mean deviation

Q: A simple random sample from a process (an infinite population) is a sample selected such that a. each element selected comes from the same population b. each element is selected independently c. each element selected comes from the same population and each element is selected independently d. the probability of being selected changes

Q: A simple random sample of size nfrom a finite population of size Nis to be selected. Each possible sample should have a. the same probability of being selected b. a probability of 1/nof being selected c. a probability of 1/Nof being selected d. a probability of N/nof being selected

Q: Excel's RAND function a. determines sample size b. selects a simple random sample c. randomizes a population d. generates random numbers

Q: A population consists of 500 elements. We want to draw a simple random sample of 50 elements from this population. On the first selection, the probability of an element being selected is a. 0.100 b. 0.010 c. 0.001 d. 0.002

Q: A population consists of 8 items. The number of different simple random samples of size 3 (without replacement) that can be selected from this population is a. 24 b. 56 c. 512 d. 128

Q: How many different samples of size 3 (without replacement) can be taken from a finite population of size 10? a. 30 b. 1,000 c. 720 d. 120

Q: number of simple random samples of size 2 (without replacement) which are possible equals a. 12 b. 15 c. 3 d. 16

Q: The number of random samples (without replacement) of size 3 that can be drawn from a population of size 5 is a. 15 b. 10 c. 20 d. 125

Q: A simple random sample of size nfrom a finite population of size Nis a sample selected such that each possible sample of size a. Nhas the same probability of being selected b. nhas a probability of 0.5 of being selected c. nhas a probability of 0.1 of being selected d. nhas the same probability of being selected

Q: The purpose of statistical inference is to provide information about the a. sample based upon information contained in the population b. population based upon information contained in the sample c. population based upon information contained in the population d. mean of the sample based upon the mean of the population

Q: A subset of a population selected to represent the population is a a. subset b. sample c. small population d. None of the alternative answers is correct.

Q: The set of all elements of interest in a study is a. set notation b. a set of interest c. a sample d. a population

Q: The finite correction factor should be used in the computation of when n/Nis greater than a. .01 b. .025 c. .05 d. .10

Q: The standard deviation of a point estimator is the a. standard error b. sample statistic c. point estimate d. sampling error

Q: A probability sampling method in which we randomly select one of the first kelements and then select every kth element thereafter is a. stratified random sampling b. cluster sampling c. systematic sampling d. convenience sampling

Q: The population being studied is usually considered ______ if it involves an ongoing process that makes listing or counting every element in the population impossible. a. finite b. infinite c. skewed d. symmetric

Q: The value of the ___________ is used to estimate the value of the population parameter. a. population statistic b. sample parameter c. population estimate d. sample statistic

Q: The standard deviation of is referred to as the a. standard x b. standard error of the mean c. sample standard mean d. sample mean deviation

Q: The standard deviation of is referred to as the a. standard proportion b. sample proportion c. average proportion d. standard error of the proportion

Q: The basis for using a normal probability distribution to approximate the sampling distribution of is a. Chebyshev's theorem b. the empirical rule c. the central limit theorem d. Bayes' theorem

Q: The expected value of equals the mean of the population from which the sample is drawn a. only if the sample size is 30 or greater b. only if the sample size is 50 or greater c. only if the sample size is 100 or greater d. for any sample size

Q: Missy Walters owns a mail-order business specializing in baby clothes. Missy is confident the dollar amounts of allher orders are normally distributed or nearly so. Assume she knows the mean and standard deviation are $249 and $46, respectively, for allorders she receives.a. Describe the sampling distribution of , where is the mean dollar-amount of an order for a sample of 10 orders.b. What is the probability that a simple random sample of 30 orders will provide an estimate of the population mean dollar-amount of an order that is within plus or minus $10 of the actual population mean?c. What happens to the sampling distribution of when the sample size is increased from 30 to 90? With a sample size of 90, what is the probability that will be between $239 and $259?

Q: Roger Hall, who oversees six Ford dealerships, believes that the colors chosen by customers who special-order their cars best reflect most customers' true color preferences. For that reason, he has tabulated the color requests specified in a sample of 56 Mustang coupe special orders placed this year. The sample data are listed below.BlackRedWhiteBlueBlueGreenRedBlackRedWhiteBlueWhiteRedRedBlackBlackGreenBlackRedBlackBlueBlackWhiteGreenBlueRedBlackWhiteBlackRedBlackBlueBlueBlackGreenWhiteBlackRedRedWhiteRedRedBlueBlackRedBlackGreenBlackGreenRedBlackWhiteBlackRedBlackWhitea. What is the point estimate of the proportion of all Mustang coupe special orders that specify a color preference of black?b. Describe the sampling distribution of , where is the proportion of Mustang coupe special orders that specify a color preference of black. Assume that the proportion of all Mustang coupe special orders having a color preference of black is .36.c. What is the probability that a simple random sample of 56 special orders will provide an estimate of the population proportion of special orders specifying the color black that is within plus or minus .05 of the actual population proportion, assuming p= .36? In other words, what is the probability that will be between .31 and .41?

Q: A random sample of ten examination papers in a course that was given on a pass or fail basis showed the following scores.Paper NumberGradeStatus165Pass287Pass392Pass435Fail579Pass6100Pass748Fail874Pass979Pass1091Passa. What is the point estimate for the mean of the population?b. What is the point estimate for the standard deviation of the population?c. What is the point estimate for the proportion of all students who passed the course?

Q: A random sample of nine telephone calls in an office provided the following information.Call NumberDuration ( Minutes)Type of Call13local28long distance34local43local55long distance66local73local85local98locala. Determine the point estimate for the average duration of all calls.b. What is the point estimate for the standard deviation of the population?c. What is the point estimate for the proportion of all calls that were long distance?

Q: The proportion of Americans who support the death penalty is 0.53. A sample of 1000 randomly selected Americans is surveyed by telephone interview. Use Excel to answer the following questions.a. What is the probability that the sample proportion of those supporting the death penalty will be less than 0.50?b. What is the probability that the sample proportion of those supporting the death penalty will be at least 0.55?c. What is the probability that the sample proportion of those supporting the death penalty will be between 0.50 and 0.55?d. For samples of size 1000, 15% of all sample proportions are at most what value?

Q: Thirty percent of a magazine's subscribers are female. A random sample of 50 subscribers is taken. Answer the following questions using Excel.a. What is the probability that the proportion of females from this sample is at most 0.25?b. What is the probability that the proportion of females from this sample is between 0.22 and 0.28?c. What is the probability that the proportion of females from this sample is within .03 of the population proportion?

Q: In a restaurant, the proportion of people who order coffee with their dinner is 0.9. A simple random sample of 144 patrons of the restaurant is taken.a. What are the expected value, standard deviation, and shape of the sampling distribution of ?b. What is the random variable in this problem? Define it in words.c. What is the probability that the proportion of people who will order coffee with their meal is between 0.85 and 0.875?d. What is the probability that the proportion of people who will order coffee with their meal is at least 0.945?

Q: Candidate A is running for president of the student government at a large university. The proportion of voters who favor the candidate is 0.8. A simple random sample of 100 voters is taken.a. What are the expected value, standard deviation, and shape of the sampling distribution of ?b. What is the probability that the number of voters in the sample who will not favor Candidate A will be between 26 and 30?c. What is the probability that the number of voters in the sample who will not favor Candidate A will be more than 16?

Q: A department store has determined that 25% of all their sales are credit sales. A random sample of 75 sales is selected.a What is the probability that the sample proportion will be greater than 0.34?b. What is the probability that the sample proportion will be between 0.196 and 0.354?c. What is the probability that the sample proportion will be less than 0.25?d. What is the probability that the sample proportion will be less than 0.10?

Q: In a local university, 10% of the students live in the dormitories. A random sample of 100 students is selected for a particular study.a. What is the probability that the sample proportion of students living in the dormitories is between 0.172 and 0.178?b. What is the probability that the sample proportion of students living in the dormitories is greater than 0.025?

Q: In a large university, 20% of the students are business majors. A random sample of 100 students is selected, and their majors are recorded.a. Compute the standard error of the proportion.b. What is the probability that the sample contains at least 12 business majors?c. What is the probability that the sample contains less than 15 business majors?d. What is the probability that the sample contains between 12 and 14 business majors?

Q: A new soft drink is being market tested. It is estimated that 60% of consumers will like the new drink. A sample of 96 taste-tested the new drink.a. Determine the standard error of the proportionb. What is the probability that more than 70.4% of consumers will indicate they like the drink?c. What is the probability that more than 30% of consumers will indicate they do notlike the drink?

Q: Ten percent of the items produced by a machine are defective. A random sample of 100 items is selected and checked for defects.a. Determine the standard error of the proportion.b. What is the probability that the sample will contain more than 2.5% defective units?c. What is the probability that the sample will contain more than 13% defective units?

Q: There are 500 employees in a firm, 45% are female. A sample of 60 employees is selected randomly.a. Determine the standard error of the proportion.b. What is the probability that the sample proportion of females is between 0.40 and 0.55?

Q: The mean diameter of a ball bearing produced by a certain manufacturer is 0.80 cm with a standard deviation of 0.03 cm. A sample of 36 ball bearings is randomly selected from a production run. Use Excel to answer the following questions.a. What is the probability that the sample of ball bearings will have a mean less than 0.798 cm?b. What is the probability that the sample of ball bearings will have a mean of at least 0.815 cm?c. What is the probability that the sample of ball bearings will have a mean between 0.798 and 0.815 cm?d. For samples of size 36, 15% of all sample means are at most what diameter?

Q: The price of a particular brand of jeans has a mean of $37.99 and a standard deviation of $7. A sample of 49 pairs of jeans is selected. Use Excel to answer the following questions.a. What is the probability that the sample of jeans will have a mean price less than $40?b. What is the probability that the sample of jeans will have a mean price between $38 and $39?c. What is the probability that the sample of jeans will have a mean price within $3 of the population mean?

Q: MNM Corporation gives each of its employees an aptitude test. The scores on the test are normally distributed with a mean of 75 and a standard deviation of 15. A simple random sample of 25 is taken from a population of 500.a. What are the expected value, the standard deviation, and the shape of the sampling distribution of ?b. What is the random variable in this problem? Define it in words.c. What is the probability that the average aptitude test score in the sample will be between 70.14 and 82.14?d. What is the probability that the average aptitude test score in the sample will be greater than 82.68?e. What is the probability that the average aptitude test score in the sample will be less than 78.69?f. Find a value, C, such that P(C) = .015.

Q: The average lifetime of a light bulb is 3,000 hours with a standard deviation of 696 hours. A simple random sample of 36 bulbs is taken.a. What are the expected value, standard deviation, and shape of the sampling distribution of ?b. What is the random variable in this problem? Define it in words.c. What is the probability that the average life in the sample will be between 2,670.56 and 2,809.76 hours?d. What is the probability that the average life in the sample will be greater than 3,219.24 hours?e. What is the probability that the average life in the sample will be less than 3,180.96 hours?

Q: Students of a large university spend an average of $5 a day on lunch. The standard deviation of the expenditure is $3. A simple random sample of 36 students is taken.a. What are the expected value, standard deviation, and shape of the sampling distribution of the sample mean?b. What is the probability that the sample mean will be at least $4?c. What is the probability that the sample mean will be at least $5.90?

Q: A bank has kept records of the checking balances of its customers and determined that the average daily balance of its customers is $300 with a standard deviation of $48. A random sample of 144 checking accounts is selected.a. What is the probability that the sample mean will be more than $306.60?b. What is the probability that the sample mean will be less than $308?c. What is the probability that the sample mean will be between $302 and $308?d. What is the probability that the sample mean will be at least $296?

Q: SAT scores have an average of 1200 with a standard deviation of 60. A sample of 36 scores is selected.a. What is the probability that the sample mean will be larger than 1224?b. What is the probability that the sample mean will be less than 1230?c. What is the probability that the sample mean will be between 1200 and 1214?d. What is the probability that the sample mean will be greater than 1200?e. What is the probability that the sample mean will be larger than 73.46?

Q: The life expectancy in the United States is 75 with a standard deviation of 7 years. A random sample of 49 individuals is selected.a. What is the probability that the sample mean will be larger than 77 years?b. What is the probability that the sample mean will be less than 72.7 years?c. What is the probability that the sample mean will be between 73.5 and 76 years?d. What is the probability that the sample mean will be between 72 and 74 years?e. What is the probability that the sample mean will be larger than 73.46 years?

Q: There are 8,000 students at the University of Tennessee at Chattanooga. The average age of all the students is 24 years with a standard deviation of 9 years. A random sample of 36 students is selected.a. Determine the standard error of the mean.b. What is the probability that the sample mean will be larger than 19.5?c. What is the probability that the sample mean will be between 25.5 and 27 years?

Q: A population of 1,000 students spends an average of $10.50 a day on dinner. The standard deviation of the expenditure is $3. A simple random sample of 64 students is taken.a. What are the expected value, standard deviation, and shape of the sampling distribution of the sample mean?b. What is the probability that these 64 students will spend a combined total of more than $715.21?c. What is the probability that these 64 students will spend a combined total between $703.59 and $728.45?

Q: An automotive repair shop has determined that the average service time on an automobile is 2 hours with a standard deviation of 32 minutes. A random sample of 64 services is selected.a. What is the probability that the sample of 64 will have a mean service time greater than 114 minutes?b. Assume the population consists of 400 services. Determine the standard error of the mean.

Q: The average weekly earnings of bus drivers in a city are $950 (that is ) with a standard deviation of $45 (that is ). Assume that we select a random sample of 81 bus drivers.a. Assume the number of bus drivers in the city is large compared to the sample size. Compute the standard error of the mean.b. What is the probability that the sample mean will be greater than $960?c. If the population of bus drivers consisted of 400 drivers, what would be the standard error of the mean?

Q: The following information gives the number of days absent from work for a population of 5 workers at a small factory.WorkerNumber of Days AbsentA5B7C1D4E8a. Find the mean and the standard deviation for the population.b. Samples of size 2 will be drawn from the population. Use the answers in part a to calculate the expected value and the standard deviation of the sampling distribution of the sample mean.c. Find all the samples of 2 workers that can be extracted from this population. Choose the samples without replacement.d. Compute the sample mean for each of the samples in Part c.e. Graph the sample means with the values of on the horizontal axis and the corresponding relative frequency on the vertical axis.