Exam 8: Sampling Methods and the Central Limit Theorem

A population consists of 15 values. How many samples of size ten are possible?

Auditors may select every 20^th file starting with say, the 5^th file in the top drawer. Then file numbers 25, 45, 65, 85, .... are audited. What type of sampling is this? _________________

Based on the central limit theorem, sampling error will decrease as sample size increases.

The mean of all possible sample means is equal to the

The standard error of the mean is directly related to the sample size.

Which sampling method would you use if every k-th item in the population sequence is selected? ______________________

In the sampling distribution of the sample means, the standard error of the mean will vary according to the size of the sample. As the sample size n gets larger, the variability of the sampling distribution of the means gets ______________.

The central limit theorem allows us to use a z-statistic to compute probabilities for the sampling distribution of the sample mean.

For a distribution of sample means constructed by sampling 5 items from a population of 15,

When using stratified random sampling, the sampling error will be zero.

The Intelligence Quotient (IQ) test scores are normally distributed with a mean of 100 and a standard deviation of 15. You enrolled in a class of 25 students. What is the probability that the class' average IQ exceeds 130?

How many different samples of size 3 can be collected from a population of ten items? ___________

The difference between the population mean and a sample mean is called _________.

Based on the central limit theorem, the sample mean can be used as a good estimator of the population mean, assuming that the size of the sample is sufficiently large.

A group of statistics students decided to conduct a survey at their university to find the average (mean) amount of time students spend studying per week. Based on a simple random sample, they surveyed 144 students. The statistics showed that students studied an average of 20 hours per week with a standard deviation of 10 hours. What is the probability that average student study time is between 18 and 22 hours?

Manufacturers were subdivided into groups by volume of sales. Those with more than $100 million in sales were classified as large; those from $50 to $100 million as medium size; and those between $25 and $50 million..., and so on. Samples were then selected from each of these groups. What is this type of sampling called?

What is the relationship of the standard deviation of the sampling distribution of the mean to the standard deviation of the population under study? ___________

An accounting firm is planning for the next tax preparation season. From last year's returns, the firm collects a systematic random sample of 100 filings. The 100 filings showed an average preparation time of 90 minutes with a standard deviation of 140 minutes. What is the standard error of the mean?

The wildlife department has been feeding a special food to rainbow trout fingerlings in a pond. Based on a large number of observations, the distribution of trout weights is normally distributed with a mean of 402.7 grams and a standard deviation 8.8 grams. What is the probability that the mean weight for a sample of 40 trout exceeds 405.5 grams?

A sampling distribution of the means is a probability distribution consisting of all possible sample means of a given sample size selected from a population.