Stats Quiz 7

A random sample of size 36 is taken from a population with mean µ = 17 and standard deviation σ = 6. What is the probability that the sample mean is less than 15? Multiple Choice 0.0228 0.3707 0.9772 0.6293

0.0228

A random sample of size 36 is taken from a population with mean µ = 23 and standard deviation σ = 6. What is the probability that the sample mean is greater than 25? Multiple Choice 0.7054 0.4316 0.0228 0.2966

0.0228

A nursery sells trees of different types and heights. These trees average 80 inches in height with a standard deviation of 19 inches. Suppose that 60 pine trees are sold for planting at City Hall. What is the standard deviation for the sample mean? Multiple Choice 9.2657 4.0187 2.4529 19

2.4529

A random sample of size 36 is taken from a population with mean µ = 22 and standard deviation σ = 6. What are the expected value and the standard deviation for the sampling distribution of the sample mean? Multiple Choice A. 22 and 1.00, respectively B. 5.425 and 2.83, respectively C. 22 and 6, respectively D. 5.425 and 1.00

22 and 1.00, respectively

Statistics are used to estimate population parameters, particularly when it is impossible or too expensive to poll an entire population. A particular value of a statistic is referred to as a(n) ______. Multiple Choice mean proportion estimate stratum

estimate

A parameter is a random variable, whereas a sample statistic is a constant.

false

Cluster sampling is preferred over other sampling techniques when the objective is to increase precision.

false

For any population X with expected value µ and standard deviation σ, the sampling distribution of X¯¯¯X¯ will be approximately normal if the sample size n is sufficiently small. As a general guideline, the normal distribution approximation is justified when n < 30.

false

For any sample size n, the sampling distribution of X¯¯¯X¯ is normal if the population from which the sample is drawn is uniformly distributed.

false

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

Selection bias occurs when the sample is mistakenly divided into strata, and random samples are drawn from each stratum.

false

Bias can occur in sampling. Bias refers to ______. Multiple Choice A. the creation of strata, which are proportional to the stratum's size B. the use of cluster sampling instead of stratified random sampling C. the division of the population into overlapping groups the tendency of a sample statistic D. to systematically overestimate or underestimate a population parameter

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

Social-desirability bias refers to systematic difference between a group's 'socially acceptable" responses to a survey or poll and this group's ultimate choice.

true

Which of the following meets the requirements of a cluster sample? Multiple Choice A. A population can be divided into 50 city blocks. The sample will include one hundred people chosen at random, without regard to the city block where they live. B. A population can be divided into 50 city blocks. The sample will include one hundred people who volunteer for the sample from any city block. C. A population can be divided into 50 city blocks. The sample will include all residents from two randomly chosen city blocks. D. A population can be divided into 50 city blocks. The sample will include two people chosen at random from each city block.

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

Which of the following is true about statistics such as the sample mean or sample proportion? Multiple Choice A. A statistic is a parameter. B. A statistic is a constant. C. A statistic is a random variable. D. A statistic is always known.

C. A statistic is a random variable.

Which of the following meets the requirements of a stratified random sample? Multiple Choice A. A population contains 10 members under the age of 25 and 20 members over the age of 25. The sample will include six people who volunteer for inclusion in the sample. B. A population contains 10 members under the age of 25 and 20 members over the age of 25. The sample will include two males chosen under the age of 25 and four females chosen over the age of 25. C. 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. D. 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 the age of 25

D. 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 the age of 25