Q&A Hero

Q: A random sample of size 100 is drawn from a population with a standard deviation of 10. If only 5% of the time a sample mean greater than 20 is obtained, the mean of the population is ______ a) 18.35 b) 16.25 c) 17.2 d) 20 e) 19

Q: A carload of steel rods has arrived at Cybermatic Construction Company. The car contains 50,000 rods. Claude Ong, manager of Quality Assurance, directs his crew measure the lengths of 100 randomly selected rods. If the population of rods has a mean length of 120 inches and a standard deviation of 0.05 inch, the probability that Claude's sample has a mean between 119.985 and 120.0125 inches is ____________. a) 0.9925 b) 0.9974 c) 0.9876 d) 0.9544 e) 0.9044

Q: A carload of steel rods has arrived at Cybermatic Construction Company. The car contains 50,000 rods. Claude Ong, manager of Quality Assurance, directs his crew measure the lengths of 100 randomly selected rods. If the population of rods have a mean length of 120 inches and a standard deviation of 0.05 inch, the probability that Claude's sample has a mean less than 119.985 inches is _____________. a) 0.9974 b) 0.0026 c) 0.4987 d) 0.0013 e) 0.0030

Q: A carload of steel rods has arrived at Cybermatic Construction Company. The car contains 50,000 rods. Claude Ong, manager of Quality Assurance, directs his crew measure the lengths of 100 randomly selected rods. If the population of rods has a mean length of 120 inches and a standard deviation of 0.05 inch, the probability that Claude's sample has a mean greater than 120.0125 inches is _____________. a) 0.0124 b) 0.0062 c) 0.4938 d) 0.9752 e) 1.0000

Q: Albert Abbasi, VP of Operations at Ingleside International Bank, is evaluating the service level provided to walk-in customers. Accordingly, he plans a sample of waiting times for walk-in customers. If the population of waiting times has a mean of 15 minutes and a standard deviation of 4 minutes, the probability that Albert's sample of 64 will have a mean between 13.5 and 16.5 minutes is ________. a) 0.9974 b) 0.4987 c) 0.9772 d) 0.4772 e) 0.5000

Q: Albert Abbasi, VP of Operations at Ingleside International Bank, is evaluating the service level provided to walk-in customers. Accordingly, he plans a sample of waiting times for walk-in customers. If the population of waiting times has a mean of 15 minutes and a standard deviation of 4 minutes, the probability that Albert's sample of 64 will have a mean less than 15 minutes is ________. a) 0.5000 b) 0.0228 c) 0.9072 d) 0.9544 e) 1.0000

Q: Albert Abbasi, VP of Operations at Ingleside International Bank, is evaluating the service level provided to walk-in customers. Accordingly, he plans a sample of waiting times for walk-in customers. If the population of waiting times has a mean of 15 minutes and a standard deviation of 4 minutes, the probability that Albert's sample of 64 will have a mean less than 16 minutes is ________. a) 0.4772 b) 0.0228 c) 0.9072 d) 0.9544 e) 0.9772

Q: Albert Abbasi, VP of Operations at Ingleside International Bank, is evaluating the service level provided to walk-in customers. Accordingly, he plans a sample of waiting times for walk-in customers. If the population of waiting times has a mean of 15 minutes and a standard deviation of 4 minutes, the probability that Albert's sample of 64 will have a mean less than 14 minutes is ________. a) 0.4772 b) 0.0228 c) 0.9772 d) 0.9544 e) 1.0000

Q: Suppose a population has a mean of 870 and a variance of 8,100. If a random sample of size 36 is drawn from the population, the probability that the sample mean is between 840 and 900 is _______. a) 0.9544 b) 0.6826 c) 0.8185 d) 0.5899 e) 0.0897

Q: Suppose a population has a mean of 870 and a variance of 1,600. If a random sample of size 64 is drawn from the population, the probability that the sample mean is between 860 and 875 is _______. a) 0.9544 b) 0.6826 c) 0.8785 d) 0.5899 e) 0.8185

Q: Suppose a population has a mean of 450 and a variance of 900. If a random sample of size 100 is drawn from the population, the probability that the sample mean is between 448 and 453 is _______. a) 0.4972 b) 0.6826 c) 0.4101 d) 0.5899 e) 0.9878

Q: Suppose a population has a mean of 400 and a standard deviation of 24. If a random sample of size 144 is drawn from the population, the probability of drawing a sample with a mean less than 402 is _______. a) 0.3413 b) 0.6826 c) 0.8413 d) 0.1587 e) 0.9875

Q: Suppose a population has a mean of 400 and a standard deviation of 24. If a random sample of size 144 is drawn from the population, the probability of drawing a sample with a mean between 395.5 and 404.5 is _______. a) 0.9756 b) 0.0244 c) 0.0278 d) 0.9722 e) 1.0000

Q: Suppose a population has a mean of 400 and a standard deviation of 24. If a random sample of size 144 is drawn from the population, the probability of drawing a sample with a mean of more than 404.5 is _______. a) 0.0139 b) 0.4861 c) 0.4878 d) 0.0122 e) 0.5000

Q: Suppose the population of all public Universities shows the annual parking fee per student is $110 with a standard deviation of $18. If a random sample of size 49 is drawn from the population, the probability of drawing a sample with a sample mean between $112 and $115 is _______. a) 0.9738 b) 0.7777 c) 0.7823 d) 0.1915 e) 1.7561

Q: Suppose the population of all public Universities shows the annual parking fee per student is $110 with a standard deviation of $18. If a random sample of size 49 is drawn from the population, the probability of drawing a sample with a sample mean between $100 and $115 is _______. a) 0.9738 b) 0.4738 c) 0.0262 d) 0.6103 e) 0.1103

Q: Suppose the population of all public Universities shows the annual parking fee per student is $110 with a standard deviation of $18. If a random sample of size 49 is drawn from the population, the probability of drawing a sample with a mean of less than $92 is _______. a) 0.3400 b) 0.1600 c) 0.0000 d) 1.0000 e) 0.7000

Q: Suppose the population of all public Universities shows the annual parking fee per student is $110 with a standard deviation of $18. If a random sample of size 49 is drawn from the population, the probability of drawing a sample with a mean of more than $115 is _______. a) 0.9738 b) 0.4738 c) 0.0262 d) 0.6103 e) 0.1103

Q: According to the central limit theorem, for samples of size 169 drawn from a population with µ = 1,014 and = 65, the standard deviation of the sampling distribution of sample means would equal _______.a) 1,014b) 65c) 15d) 6e) 5

Q: According to the central limit theorem, for samples of size 169 drawn from a population with µ = 1,014 and = 65, the mean of the sampling distribution of sample means would equal _______.a) 1,014b) 65c) 5d) 6e) 3

Q: According to the central limit theorem, for samples of size 64 drawn from a population with µ = 800 and = 56, the standard deviation of the sampling distribution of sample means would equal _______.a) 7b) 8c) 100d) 800e) 80

Q: According to the central limit theorem, for samples of size 64 drawn from a population with µ = 800 and = 56, the mean of the sampling distribution of sample means would equal _______.a) 7b) 8c) 100d) 800e) 80

Q: Decreasing the sample size causes the sampling distribution of to ________. a) shift to the right b) shift to the left c) have more dispersion d) have less dispersion e) stay unchanged

Q: According to the central limit theorem, if a sample of size 64 is drawn from a population with a standard deviation of 80, the standard deviation of sample means would equal _______. a) 10.000 b) 1.250 c) 0.125 d) 0.800 e) 0.080

Q: According to the central limit theorem, if a sample of size 100 is drawn from a population with a standard deviation of 80, the standard deviation of sample means would equal _______. a) 0.80 b) 8 c) 80 d) 800 e) 0.080

Q: According to the central limit theorem, if a sample of size 56 is drawn from a population with a standard deviation of 14, the standard deviation of the distribution of the sample means would equal _______. a) 14 b) 1.87 c) 3.5 d) 0.25 e) 3.74

Q: According to the central limit theorem, if a sample of size 56 is drawn from a population with a mean of 16, the mean of all sample means would equal _______. a) 56 b) 16 c) 7.5 d) 44.0 e) 196

Q: According to the central limit theorem, if a sample of size 100 is drawn from a population with a mean of 80, the mean of all sample means would equal _______. a) 0.80 b) 8 c) 80 d) 100 e) 120

Q: Catherine Chao, Director of Marketing Research, needs a sample of households to participate in the testing of a new toothpaste package. She directs the seven members of her staff to find five households each. Catherine's sample is a _____________. a) cluster sample b) proportionate stratified sample c) quota sample d) disproportionate stratified sample e) simple random sample

Q: Catherine Chao, Director of Marketing Research, needs a sample of households to participate in the testing of a new toothpaste package. She chooses thirty-six of her closest friends. Catherine's sample is a _____________. a) cluster sample b) convenience sample c) quota sample d) systematic sample e) random sample

Q: Abel Alonzo, Director of Human Resources, is exploring employee absenteeism at the Harrison Haulers Plant. Abel knows that absenteeism varies significantly between departments. For example, workers in the wood shop are absent more than those in the tuning department and the size of the departments ranges from 40 to 120 workers. He orders a random sample of 10% of the workers from each of the six departments. Abel's sample is a ________________. a) proportionate systematic sample b) proportionate stratified sample c) disproportionate systematic sample d) disproportionate stratified sample e) proportionate cluster sample

Q: Abel Alonzo, Director of Human Resources, is exploring employee absenteeism at the Harrison Haulers Plant. Abel knows that absenteeism varies significantly between departments. For example, workers in the wood shop are absent more than those in the tuning department and the size of the departments ranges from 40 to 120 workers. He orders a random sample of 10 workers from each of the six departments. Abel's sample is a ________________. a) proportionate systematic sample b) proportionate stratified sample c) disproportionate systematic sample d) disproportionate stratified sample e) proportionate cluster sample

Q: A carload of steel rods has arrived at Cybermatic Construction Company. The car contains 1,000 bundles of 50 rods each. Claude Ong, manager of Quality Assurance, directs the receiving crew to deliver the 63rd and 458th bundles to his crew for 100% inspection. Claude randomly selected 63 and 458 from a table of random numbers. Claude's sample of 100 rods is a _____________. a) cluster sample b) simple random sample c) quota sample d) systematic sample e) stratified sample

Q: A carload of palletized aluminum castings has arrived at Mansfield Motor Manufacturers. The car contains 1,000 pallets of 100 castings each. Mario Munoz, manager of Quality Assurance, directs the receiving crew to deliver the 127th and 869th pallets to his crew for 100% inspection. Mario randomly selected 127 and 869 from a table of random numbers. Mario's sample of 200 castings is a _____________. a) simple random sample b) systematic sample c) stratified sample d) cluster sample e) convenience sample

Q: Albert Abbasi, VP of Operations at Ingleside International Bank, is evaluating the service level provided to walk-in customers. Accordingly, he plans a sample of waiting times for walk-in customers. Albert randomly selects 4 as a starting point and instructs his staff to record the waiting times for the 4th walk-in customer and every 10th customer thereafter (4, 14, 24, etc.). Albert's sample is a ________. a) simple random sample b) cluster sample c) convenience sample d) stratified sample e) systematic sample

Q: Albert Abbasi, VP of Operations at Ingleside International Bank, is evaluating the service level provided to walk-in customers. Accordingly, he plans a sample of waiting times for walk-in customers. Albert instructs his staff to record the waiting times for the first 45 walk-in customers arriving after the noon hour. Albert's sample is a ________. a) simple random sample b) systematic sample c) convenience sample d) stratified sample e) cluster sample

Q: On Saturdays, cars arrive at David Zebda's Scrub and Shine Car Wash at the rate of 80 cars per hour during the ten-hour shift. David wants a sample of 40 Saturday customers to answer the long version of his quality service questionnaire. He randomly selects 9 as a starting point and instructs the crew to select the 9th customer and each customer at intervals of 20 (9, 29, 49, etc.). His sample is a __________. a) convenience sample b) simple random sample c) unsystematic sample d) stratified sample e) systematic sample

Q: On Saturdays, cars arrive at David Zebda's Scrub and Shine Car Wash at the rate of 80 cars per hour during the ten-hour shift. David wants a sample of 40 Saturday customers to answer the long version of his quality service questionnaire. He instructs the Saturday crew to select the first 40 customers. His sample is a __________. a) convenience sample b) simple random sample c) systematic sample d) stratified sample e) cluster sample

Q: Financial analyst Larry Potts needs a sample of 100 securities listed on either the New York Stock Exchange (NYSE) or the American Stock Exchange (AMEX). According to the Wall Street Journal's "Stock Market Data Bank," 2,531 NYSE securities and AMEX 746 securities were traded on the previous business day. Larry directs his staff to randomly select 77 NYSE and 23 AMEX securities. His sample is a ____________. a) disproportionate systematic sample b) disproportionate stratified sample c) proportionate stratified sample d) proportionate systematic sample e) proportionate cluster sampling

Q: Financial analyst Larry Potts needs a sample of 100 securities listed on the New York Stock Exchange. In the current issue of the Wall Street Journal, 2,531 securities are listed in the "New York Exchange Composite Transactions," an alphabetical listing of all securities traded on the previous business day. Larry randomly selects the 7th security as a starting point, and selects every 25th security thereafter (7, 32, 57, etc.). His sample is a ____________. a) quota sample b) simple random sample c) stratified sample d) systematic sample e) cluster sample

Q: Financial analyst Larry Potts needs a sample of 100 securities listed on the New York Stock Exchange. In the current issue of the Wall Street Journal, 2,531 securities are listed in the "New York Exchange Composite Transactions," an alphabetical listing of all securities traded on the previous business day. Larry uses a table of random numbers to select 100 numbers between 1 and 2,531. His sample is a ____________. a) quota sample b) simple random sample c) systematic sample d) stratified sample e) cluster sample

Q: Pinky Bauer, Chief Financial Officer of Harrison Haulers, Inc., suspects irregularities in the payroll system. She knows that 2,500 payroll vouchers have been issued since January 1, 2000, and her staff doesn't have time to inspect each voucher. So, she randomly selects 53 as a starting point and orders her staff to inspect the 53rd voucher and each voucher at an increment of 100 (53, 153, 253, etc.). Her sample is a ___________. a) stratified sample b) simple random sample c) convenience sample d) cluster sample e) systematic sample

Q: Pinky Bauer, Chief Financial Officer of Harrison Haulers, Inc., suspects irregularities in the payroll system. She knows that 2,500 payroll vouchers have been issued since January 1, 2000, and her staff doesn't have time to inspect each voucher. So, she orders her staff to inspect the last 200 vouchers. Her sample is a ___________. a) stratified sample b) simple random sample c) convenience sample d) systematic sample e) cluster sample

Q: Inquiries arrive at a record message device according to a Poisson process of rate 15 inquiries per minute. The probability that it takes more than 12 seconds for the first inquiry to arrive is approximately _________ a) 0.05 b) 0.75 c) 0.25 d) 0.27 e) 0.73

Q: Participants in a 2 day biking event, cross the finish line at a rate of 10 bike riders per fifteen minute interval. The probability that less than 10 minutes will elapse between car arrivals is _____________.a) .0001b) .9987c) .0013d) .6667e) .1667

Q: Participants in a 2 day biking event, cross the finish line at a rate of 10 bike riders per fifteen minute interval. The probability that at least 2 minutes will elapse between bike riders is _____________.a) .0000b) .0498c) .2635d) .1353e) .4647

Q: Participants in a 2 day biking event, cross the finish line at a rate of 10 bike riders per fifteen minute interval. On average, how much time, in minutes, elapses between bike riders? a) 1.50 b) .0667 c) .1667 d) 1.00 e) 2.50

Q: At a certain workstation in an assembly line, the time required to assemble a component is exponentially distributed with a mean time of 10 minutes. Find the probability that a component is assembled in 3 to 7 minutes? a) 0.5034 b) 0.2592 c) 0.2442 d) 0.2942 e) 0.5084

Q: At a certain workstation in an assembly line, the time required to assemble a component is exponentially distributed with a mean time of 10 minutes. Find the probability that a component is assembled in 7 minutes or less? a) 0.349 b) 0.591 c) 0.286 d) 0.714 e) 0.503

Q: The average time between phone calls arriving at a call center is 30 seconds. Assuming that the time between calls is exponentially distributed, find the probability that less than two minutes elapse between calls. a) 0.018 b) 0.064 c) 0.936 d) 0.982 e) 1.000

Q: The average time between phone calls arriving at a call center is 30 seconds. Assuming that the time between calls is exponentially distributed, find the probability that more than a minute elapses between calls. a) 0.135 b) 0.368 c) 0.865 d) 0.607 e) 0.709

Q: For an exponential distribution with a lambda (l) equal to 20, the mean equal to _______. a) 20 b) .05 c) 4.474 d) 1 e) 2.11

Q: The exponential distribution is an example of _______. a) a discrete distribution b) a continuous distribution c) a bimodal distribution d) a normal distribution e) a symmetrical distribution

Q: The probability that a call to an emergency help line is answered in less than 10 seconds is 0.8. Assume that the calls are independent of each other. Using the normal approximation for binomial with a correction for continuity, the probability that at least 75 of 100 calls are answered within 10 seconds is approximately _______a) 0.8b) 0.1313c) 0.5235d) 0.9154e) 0.8687

Q: Assuming an equal chance of a new baby being a boy or a girl (that is, p= 0.5), wewould like to find the probability of 40 or more of the next 100 births at a local hospital will be boys. Using the normal approximation for binomial with acorrection for continuity, we should use the z-score _______ a) 0.4 b) -2.1 c) 0.6 d) 2 e) -1.7

Q: Let xbe a binomial random variable withn=50 andp=.3. The probability of less than or equal to13 successes, when using the normal approximation for binomial is ____ ____ a) -.6172 b) .3086 c) 3.240 c) .2324 d) .2676 e) -.23224

Q: Let xbe a binomial random variable withn=50 andp=.3. If we use the normal distribution to approximate probabilities for this, a correction for continuity should be made. To find the probability of more than 15 successes, we should find _______. a) P(x>15.5) b) P(x>15) c) P(x>14.5) d) P(x<14.5) e) P(x< 15)

Q: Let xbe a binomial random variable withn=35 andp=.20. If we use the normal distribution to approximate probabilities for this, we would use a mean of _______. a) 35 b) 20 c) 70 d) 7 e) 3.5

Q: Completion time (from start to finish) of a building remodeling project is normally distributed with a mean of 200 work-days and a standard deviation of 10 work-days. To be 99% sure that we will not be late in completing the project, we should request a completion time of _______ work-days. a) 211 b) 207 c) 223 d) 200 e) 250

Q: Completion time (from start to finish) of a building remodeling project is normally distributed with a mean of 200 work-days and a standard deviation of 10 work-days. The probability that the project will be completed within 185 work-days is ______. a) 0.0668 b) 0.4332 c) 0.5000 d) 0.9332 e) 0.9950

Q: The net profit from a certain investment is normally distributed with a mean of $2,500 and a standard deviation of $1,000.. The probability that the investor's net gain will be at least $2,000 is _____________. a) 0.0000 b) 0.3413 c) 0.0005 d) 0.0500 e) 0.5000

Q: The net profit from a certain investment is normally distributed with a mean of $2,500 and a standard deviation of $1,000. The probability that the investor will not have a net loss is _____________. a) 0.4938 b) 0.0062 c) 0.9938 d) 0.5062 e) 0.0000

Q: Sure Stone Tire Company has established that the useful life of a particular brand of its automobile tires is normally distributed with a mean of 40,000 miles and a standard deviation of 5000 miles. What is the probability that a randomly selected tire of this brand has a life between 30,000 and 50,000 miles? a) 0.5000 b) 0.4772 c) 0.9544 d) 0.9772 e) 1.0000

Q: Sure Stone Tire Company has established that the useful life of a particular brand of its automobile tires is normally distributed with a mean of 40,000 miles and a standard deviation of 5000 miles. What is the probability that a randomly selected tire of this brand has a life of at least 50,000 miles? a) 0.0228 b) 0.9772 c) 0.5000 d) 0.4772 e) 1.0000

Q: Sure Stone Tire Company has established that the useful life of a particular brand of its automobile tires is normally distributed with a mean of 40,000 miles and a standard deviation of 5000 miles. What is the probability that a randomly selected tire of this brand has a life of at most 30,000 miles? a) 0.5000 b) 0.4772 c) 0.0228 d) 0.9772 e) 1.0000

Q: Suppose you are working with a data set that is normally distributed with a mean of 400 and a standard deviation of 20. Determine the value of xsuch that 60% of the values are greater than x. a) 404.5 b) 395.5 c) 405.0 d) 395.0 e) 415.0

Q: The expected (mean) life of a particular type of light bulb is 1,000 hours with a standard deviation of 50 hours. The life of this bulb is normally distributed. What is the probability that a randomly selected bulb would last fewer than 940 hours? a) 0.3849 b) 0.8849 c) 0.1151 d) 0.6151 e) 0.6563

Q: The expected (mean) life of a particular type of light bulb is 1,000 hours with a standard deviation of 50 hours. The life of this bulb is normally distributed. What is the probability that a randomly selected bulb would last fewer than 1100 hours? a) 0.4772 b) 0.9772 c) 0.0228 d) 0.5228 e) 0.5513

Q: The expected (mean) life of a particular type of light bulb is 1,000 hours with a standard deviation of 50 hours. The life of this bulb is normally distributed. What is the probability that a randomly selected bulb would last longer than 1150 hours? a) 0.4987 b) 0.9987 c) 0.0013 d) 0.5013 e) 0.5513

Q: Suppose the total time to fill a routine prescription at a local pharmacy is 35 minutes based on the time the physician places the order to the time it is dispensed. Assume the standard deviation is 11 minutes and the zscore is 0. What is x? a) -35.0 b) 0.0 c) 70.0 d) 35.0 e) -1.0

Q: Suppose the total time to fill a routine prescription at a local pharmacy is 35 minutes based on the time the physician places the order to the time it is dispensed. Assume the standard deviation is 11 minutes and the zscore is -1.3. What is x? a) 20.7 b) 0.0 c) -14.3 d) 14.3 e) -20.7

Q: Suppose the total time to fill a routine prescription at a local pharmacy is 35 minutes based on the time the physician places the order to the time it is dispensed. Assume the standard deviation is 11 minutes.. A zscore was calculated for a number, and the zscore is 3.4. What is x?a) 37.4b) 72.4c) 0.00d) 68.0e) 2.0.8

Q: Suppose the total time to fill a routine prescription at a local pharmacy is 35 minutes based on the time the physician places the order to the time it is dispensed. Assume the standard deviation is 11 minutes. the z-score for x = 46 is ________. a) 1.0 b) -1.0 c) 11 d) -11 e) .10

Q: Within a range of zscores from -2 to +2, you can expect to find _______ per cent of the values in a normal distribution. a) 95 b) 99 c) 68 d) 34 e) 100

Q: Within a range of zscores from -1 to +1, you can expect to find _______ per cent of the values in a normal distribution. a) 95 b) 99 c) 68 d) 34 e) 100

Q: A zscore is the number of __________ that a value is from the mean. a) variances b) standard deviations c) units d) miles e) minutes

Q: Let zbe a normal random variable with mean 0 and standard deviation 1. The 90thpercentile of zis ____________. a) 1.645 b) -1.254 c) 1.960 d) 1.280 e) 1.650

Q: Let zbe a normal random variable with mean 0 and standard deviation 1. The 75thpercentile of zis ____________. a) 0.6700 b) -1.254 c) 0.0000 d) 1.2800 e) 0.5000

Q: Let zbe a normal random variable with mean 0 and standard deviation 1. The 50thpercentile of zis ____________. a) 0.6700 b) -1.254 c) 0.0000 d) 1.2800 e) 0.5000

Q: Let zbe a normal random variable with mean 0 and standard deviation 1. What is P(-2.25 < z< -1.1)?a) 0.3643b) 0.8643c) 0.1235d) 0.4878e) 0.5000