Exam 7: Sampling and Sampling Distributions

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 ____________.

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 _______.

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 _______.

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 _____________.

Alice Zhong is the VP of operations at Pearl Financial Services.She wants to measure customer satisfaction after a new website and other changes were introduced a few months ago.For this purpose,she instructs her staff to prepare a questionnaire and send it to the clients that access the company's website during from 8 a.m.to 9 a.m.for the next four weeks.This is an example of ______.

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 _______.

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 _______.

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 ________________.

If random variable X is distributed according to a uniform distribution between 0 and 1 (X ~ U[0,1]),and 100 random samples of sizes 35-40 were taken,the sum of the sample means would be ______.

Pinky Bauer,Chief Financial Officer of Harrison Haulers,Inc.,suspects irregularities in the payroll system. If 10% of the 5,000 payroll vouchers issued since January 1,2000,have irregularities,the probability that Pinky's random sample of 200 vouchers will have a sample proportion of between .06 and .14 is ___________.

The sampling distribution of is close to normal provided that n≥30.

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.

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 _______.

Suppose 65% of all college students have a laptop computer at home and a sample of 150 students is taken.The mean of the sampling distribution of is

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 _______.

If every unit of the population has the same probability of being selected to the sample,then the researcher is conducting random sampling.

Decreasing the sample size causes the sampling distribution of to ________.

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

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 ________.

Certain transportation company has a fleet of 210 vehicles.The average age of the vehicles is 4.25 years,with a standard deviation of 18 months.In a random sample of 40 vehicles,what is the probability that the average age of vehicles in the sample will be less than 4 years?