From a group of six people， two individuals are to be selected at random. How many possible selections are possible? 答案: 15

From a group of six people， two individuals are to be selected at random. How many possible selections are possible?

答案: 15

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相关试题

A method of assigning probabilities based upon judgment is referred to as the

答案: subjective method

A graphical device used for enumerating sample points in a multiple-step experiment is a

答案: None of these alternatives is correct.

Two events are mutually exclusive

答案: if they have no sample points in common

Events that have no sample points in common are

答案: mutually exclusive events

Initial estimates of the probabilities of events are known as

答案: prior probabilities

The addition law is potentially helpful when we are interested in computing the probability of

答案: the union of two events

The sum of the probabilities of two complementary events is

答案: 1.0

The set of all possible outcomes of an experiment is

答案: the sample space

If a six sided die is tossed two times and “3” shows up both times， the probability of “3” on the third trial is

答案: 1/6

Given that event E has a probability of 0.31， the probability of the complement of event E

答案: 0.69

Bayes’ theorem is used to compute

答案: the posterior probabilities

The multiplication law is potentially helpful when we are interested in computing the probability of

答案: the intersection of two events

If P(A) = 0.5 and P(B) = 0.5， then P(A Ç B)

答案: None of these alternatives is correct.

A lottery is conducted using three urns. Each urn contains chips numbered from 0 to 9. One chip is selected at random from each urn. The total number of sample points in the sample space is

答案: 1，000

An experiment consists of four outcomes with P(E1) = 0.2， P(E2) = 0.3， and P(E3) = 0.4. The probability of outcome E4 is

答案: 0.100

The set of all possible sample points (experimental outcomes) is called

答案: the sample space

Events A and B are mutually exclusive if their joint probability is zero.

答案: 正确

If two events are mutually exclusive， then their intersection can have any value larger than zero.

答案: 错误

A method of assigning probabilities which assumes that the experimental outcomes are equally likely is referred to as the classical method.

答案: 正确

A method of assigning probabilities based on historical data is called the historical method.

答案: 错误

The probability assigned to each experimental outcome must be between zero and one.

答案: 正确

A measure of the average value of a random variable is called a(n) expected value.

答案: 正确

Chapter 5 Survey Sampling quizzes5

Parameters are

答案: numerical characteristics of a population

A simple random sample of 100 observations was taken from a large population. The sample mean and the standard deviation were determined to be 80 and 12 respectively. The standard error of the mean is

答案: 1.20

A population has a standard deviation of 16. If a sample of size 64 is selected from this population， what is the probability that the sample mean will be within ±2 of the population mean?

答案: 0.6826

Convenience sampling is an example of

答案: nonprobabilistic sampling

Which of the following is an example of nonprobabilistic sampling?

答案: judgment sampling

Stratified random sampling is a method of selecting a sample in which

答案: the population is first divided into strata， and then random samples are drawn from each stratum

A population consists of 500 elements. We want to draw a simple random sample of 50 elements from this population. On the first selection， the probability of an element being selected is

答案: 0.002

As the sample size increases， the

答案: standard error of the mean decreases

If we consider the simple random sampling process as an experiment， the sample mean is

答案: a random variable

As the sample size becomes larger， the sampling distribution of the sample mean approaches a

答案: normal distribution

The standard deviation of a sample of 100 elements taken from a very large population is determined to be 60. The variance of the population

答案: can be any value greater or equal to zero

A probability distribution for all possible values of a sample statistic is known as

答案: a sampling distribution

A population has a mean of 300 and a standard deviation of 18. A sample of 144 observations will be taken. The probability that the sample mean will be between 297 to 303 is

答案: 0.8664

A theorem that allows us to use the normal probability distribution to approximate the sampling distribution of sample means and sample proportions whenever the sample size is large is known as the

答案: central limit theorem

A sample of 400 observations will be taken from an infinite population. The population proportion equals 0.8. The probability that the sample proportion will be greater than 0.83 is

答案: 0.0668

Which of the following is(are) NOT point estimator(s)?

答案: s;
m;
a

Which of the following is an example of probability sampling?

答案: simple random sampling;
stratified simple random sampling;
systematic sampling;
cluster sampling

Which of the following is an example of non probability sampling?

答案: convenience sampling;
judgment sampling

The error that occurs because a sample， and not the entire population， is used to estimate a population parameter is a sampling error.

答案: 正确

Cluster sampling is a non probability sampling method.

答案: 错误

A method of selecting a sample by randomly selecting the first element and then selecting every Kth element thereafter is stratified simple random sampling

答案: 错误

In a sample survey， it is common practice to use a t value of (when approximating a 95% confidence interval)

答案: 错误

A sampling unit must have one element.

答案: 错误

Conclusions drawn from a sample survey apply to any population.

答案: 错误