Exam 7: Sampling and Sampling Distributions

Sampling errors cannot by determined objectively for nonrandom sampling techniques.

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 ___________.

The sampling distribution of has a mean equal to the square root of the population proportion p.

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 _____________.

In some situations,sampling may be the only option because the population is inaccessible.

Increasing the sample size causes the numerical value of standard error of the sample means to increase.

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 _______.

The standard deviation of a sampling distribution of the sample means is commonly called the standard error of the mean.

Paige DeMarco is the Vice President for University Advancement at State University.She is responsible for the capital campaign to raise money for the new student services building.Paige selects the first 100 alumni listed on a web-based social networking site for State University.She intends to contact these individuals regarding possible donations.Her sample is a _________.

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 _____________.

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 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 ____________.

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 sampling distribution is the distribution of a sample statistic such as the sample mean or sample proportion.

Paige DeMarco is the Vice President for University Advancement at State University.She is responsible for the capital campaign to raise money for the new student services building.Paige plans to target alumni and acquires her sampling frame from the State University Office of Alumni Relations.She intends to contact these individuals regarding possible donations.Paige chooses her sample by selecting six-digit numbers (1 to 150,000)from a random number table.Her sample is a _________.

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 _______.

Cluster (or area)sampling is a type of random sampling technique.

If the population proportion is 0.90 and a sample of size 64 is taken,what is the probability that the sample proportion is more than 0.89?

The central limit theorem states that if the sample size,n,is large enough (n ≥20),the distribution of the sample means is normally distributed regardless of the shape of the population.

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 ________.