Ch. 7 Stats

Which of the following meets the requirements of a cluster sample?

A population can be divided into 50 city blocks. The sample will include residents from two randomly chosen city blocks.

Which of the following meets the requirements of a simple random sample?

A population contains 10 members under the age of 25 and 20 members over the age of 25. The sample will include six people chosen at random, without regard to age.

The central limit theorem states that, for any distribution, as n gets larger, the sampling distribution of the sample mean ________.

is closer to a normal distribution

Using the central limit theorem, applied to the sampling distribution of the sample proportion, what conditions must be met?

np≥5 and n(1−p)≥5

Selection bias occurs when ________.

portions of the population are systematically underrepresented in the sample due to the constraints of the sample design

If a population is known to be normally distributed, what can be said of the sampling distribution of the sample mean drawn from this population? Formula

se(/X)=o/n-1

In any production process, variations in the quality of the end product are inevitable. Assignable variation refers to ______.

specific events or factors that can usually be identified and eliminated

What is the relationship between the standard deviation of the sample mean and the population standard deviation?

se(/X)= o/sqrt(n)

Susan has been on a bowling team for 14 years. After examining all of her scores over that period of time, she finds that they follow a normal distribution. Her average score is 225, with a standard deviation of 13. If during a typical week Susan bowls 16 games, what is the probability that her average score is more than 230?

0.0620

A random sample of size 100 is taken from a population described by the proportion p = 0.60. The probability that the sample proportion is less than 0.55 is ________.

0.1537

Suppose that, on average, electricians earn approximately μ = $54,000 per year in the United States. Assume that the distribution for electricians' yearly earnings is normally distributed and that the standard deviation is o = $12,000.

0.1587

The labor force participation rate is the number of people in the labor force divided by the number of people in the country who are of working age and not institutionalized. The BLS reported in February 2012 that the labor force participation rate in the United States was 63.7% (Calculatedrisk.com). A marketing company asks 120 working-age people if they either have a job or are looking for a job, or, in other words, whether they are in the labor force. What is the probability that fewer than 60% of those surveyed are members of the labor force?

0.1996

A random sample of size 100 is taken from a population described by the proportion p = 0.60. The probability that the sample proportion is greater than 0.62 is ________.

0.3415

Nonresponse bias occurs when ______.

Those responding to a survey or poll differ systematically from the non-respondents

Professor Elderman has given the same multiple-choice final exam in his Principles of Microeconomics class for many years. After examining his records from the past 10years, he finds that the scores have a mean of 76 and a standard deviation of 12. What is the probability that a class of 15 students will have a class average greater than 70 on Professor Elderman's final exam?

Cannot be determined.

What is the relationship between the expected value of the sample mean and the expected value of the population?

E(X)=E(X)=u

In cluster random sampling, the population is first divided up into mutually exclusive and collectively exhaustive groups, called clusters. A cluster sample includes randomly selected observations from each cluster, which are proportional to the cluster's size.

FALSE

The standard deviation of the sample mean suggests that the variation between observations is smaller than the variation between averages

FALSE

If a population is known to be normally distributed, what can be said of the sampling distribution of the sample mean drawn from this population? Sample size

For any sample size n, the sampling distribution of the sample mean is normally distributed.

Which of the following is not a form of bias?

Information from the sample is typical of information in the population.

A simple random sample is a sample of n observations that has the same probability of being selected from the population as any other sample of n observations.

TRUE

In stratified random sampling, the population is first divided up into mutually exclusive and collectively exhaustive groups, called strata. A stratified sample includes randomly selected observations from each stratum, which are proportional to the stratum's size.

TRUE

Nonresponse bias occurs when those responding to a survey or poll differ systematically from the nonrespondents.

TRUE

In any production process, variation in the quality of the end product is inevitable. Chance variation, or common variation, refers to ______.

a number of randomly occurring events that are part of the production process

According to the central limit theorem, the distribution of the sample means is normal if ______.

the sample size n ≥ 30

Bias can occur in sampling. Bias refers to ______.

the tendency of a sample statistic to systematically over or underestimate a population parameter

Which of the following is considered an estimate?

x=20

A random sample of size 100 is taken from a population described by the proportion p = 0.60. What are the expected value and the standard error for the sampling distribution of the sample proportion?

0.600 and 0.049

The labor force participation rate is the number of people in the labor force divided by the number of people in the country who are of working age and not institutionalized. The BLS reported in February 2012 that the labor force participation rate in the United States was 63.7% (Calculatedrisk.com). A marketing company asks 120 working-age people if they either have a job or are looking for a job, or, in other words, whether they are in the labor force. What are the expected value and the standard error for a labor participation rate in the company's sample?

0.637 and 0.0439

A nursery sells trees of different types and heights. These trees average 60 inches in height with a standard deviation of 16 inches. Suppose that 75 pine trees are sold for planting at City Hall. What is the standard deviation for the sample mean?

1.85

A packaging company strives to maintain a constant temperature for its packages that 25) require a specific temperature range. It is believed that the temperature of packagesfollows a normal distribution with a mean of 5 degrees Celsius and a standard deviationof 0.3 degree Celsius. Inspectors take weekly samples for 5 weeks of eight randomly selected boxes and report their temperatures. The five weekly sample means are shown in the table below. How many points are outside the control limits?

2

Suppose that, on average, electricians earn approximately µ = $54,000 per year in the United States. Assume that the distribution for electricians' yearly earnings is normally distributed and that the standard deviation is σ = $12,000. Given a sample of four electricians, what is the standard deviation for the sampling distribution of the sample mean?

6,000

Which of the following meets the requirements of a stratified random sample?

A population contains 10 members under the age of 25 and 20 members over the age of 25. The sample will include two people chosen at random under the age of 25 and four people chosen at random over 25.