Chapter 8

The average height of American women (in 2016) is 5 ft. 4 inches (64 inches) with a standard deviation of 3 inches. What is the probability that the average height of a random group of nine American women would be less than five feet three inches? Assume that the heights of American women are normally distributed.

0.1587

A marketing firm is polling 60 students at a college using a stratified sample. If two thirds of the students are women, and one quarter of the students are from out of state, how many out-of-state students should be polled?

15

Other reasons besides cost and size may make it difficult or impossible to evaluate the entire population. Which of the following describe such reasons? Select all that apply.

A large part of the population may be physically inaccessible. The population may be changing too fast to allow complete sampling.

Other reasons besides cost and size may make it difficult or impossible to evaluate the entire population. Which of the following describe such reasons? Select all that apply.

A large part of the population may be physically inaccessible. The population may be changing too fast to allow complete sampling.

Choose the statement that best defines the Sampling Distribution of the Sample Mean.

A probability distribution of all possible sample means of a given sample size.

Which of the following statements correctly describe the relationship between a population and a sample? Select all that apply.

A sample is a subset of the population. Samples are used to estimate population characteristics. A sample statistic is probably not exactly the same as the corresponding population characteristic

What is a simple random sample? Choose one.

A sample selected so that each member of the population has the same likelihood of being included.

Which one of the following statements is true about the dispersion of the distribution of sample means?

As the sample size increases, the variability in the sample means decreases.

Which of the following populations is a good candidate for Systematic random sampling?

Companies listed on the New York Stock Exchange.

Which of the following statements describe valid reasons to use a sample instead of evaluating a much larger population? Select all that apply.

Contacting the whole population would be only marginally more accurate than a sample. Contacting the entire population would be time consuming.

Identify the steps involved in taking a cluster sample. Select all that apply.

Select a random sample from each sub group. Divide the population into groups using naturally occurring boundaries. Randomly select a subset of clusters.

Identify the steps required in taking a systematic random sample. Select all that apply.

Select every kth member of the population from the starting point. Select a random starting point.

Why is systematic random sampling sometimes used in place of simple random sampling?

Sometimes it is difficult to assign random numbers.

Which of the following distinguish systematic random sampling from simple random sampling? Select all that apply.

Systematic random sampling uses only one random choice, instead of several. Systematic random sampling is quicker and easier.

Identify the steps that are followed in taking a stratified random sample. Select all that apply.

Take random samples from each strata. Determine what portion of the sample should come from each strata. Measure the size of the strata as a proportion of the population.

Choose the statement that best describes sampling error.

The difference between a sample statistic and its corresponding population parameter.

Which of the following statements are true features of the Central Limit Theorem?

The distribution shape is approximately Normal. It describes the sampling distribution of the sample mean. For large sample size, the distribution of sample means is independent of the shape of the population.

In using a random number table to select a simple random sample, where does "randomness" occur in the process? Select all that apply.

The manner in which numbers are taken from the table. The table itself is the one source of randomness.

Which statement correctly describes the relationship between the mean of the sample means and the population mean?

The mean of the sample means equals the population mean.

What characteristic of a population requires the use of stratified random sampling to avoid bias?

The population is clearly divided into groups based on some characteristic.

What characteristic of a population makes it a good candidate for cluster sampling?

The population is widely scattered over a large geographical area.

The Central Limit Theorem describes an expected distribution shape. Which of these statements is correct?

The sampling distribution of the sample mean is nearly normal.

Which of the following statements about the sampling distribution of the sample means is not correct?

The standard deviation of the sample means is the same as that of the population.

Pick the statement that describes the formula for the standard error of the mean in ordinary language.

The standard error is equal to the population standard deviation divided by the square root of the sample size.

Which of the populations listed below is a natural candidate for cluster sampling?

The voters in a state, who are grouped into political districts.

The shape of a sampling distribution tends to follow the normal probability distribution.

True

There are many reasons why it may be undesirable to sample an entire population. Which of the following is a reason that a modest size sample may be adequate?

Very few problems require 100% accuracy.

There are two conditions under which we can assume that the sample means to follow a normal distribution. What are they?

We don't know the population distribution, but the sample size is 30 or larger. We know that the population is normally distributed.

When is it inappropriate to use systematic random sampling?

When the order of items in the population is related to some particular characteristic.

Which of the following is an expression that represents sampling error?

Xbar-u

In cluster sampling the clusters are chosen from the population using simple random sampling. What kind of sampling is used within the individual clusters?

Random sampling

"Destructive Testing" destroys a sample in the course of measuring it. Which of the following are examples of this process? Select all that apply.

Determining a table's maximum load capacity by increasing its load until it breaks. Evaluating coffee for taste and aroma.

If a researcher was studying semester loads of students, which of the following might represent strata that would be appropriate for stratified random sampling? Select all that apply.

Grouping students by marital status. Grouping students as employed and unemployed.

Choose the two statements that are correct descriptions of the sampling distribution of the sample mean.

It is a probability distribution of all possible sample means. It is a distribution of means from samples of all one size.

Economics plays a role in the sampling process. Which statements correctly describe this relationship?

Larger samples cost more, and increasing size gives diminishing marginal returns in accuracy. The cost of studying an entire population may be prohibitive.

The manner in which numbers are taken from the table. The table itself is the one source of randomness.

Larger samples cost more, and increasing size gives diminishing marginal returns in accuracy. The cost of studying an entire population may be prohibitive.

How is a table of random numbers used to select a random sample? Choose the steps that make up the process.

items whose numbers correspond to random numbers become the sample numbers are chosen systematically from the random number table Items from the population are assigned sequential numbers.