举一反三
- A sample of size 40 is to be taken from an infinite population whose mean and standard deviation are 68 and 12, respectively. The probability that the sample mean will be larger than 70 is:
- Given an infinite population with a mean of 75 and a standard deviation of 12, the probability that the mean of a sample of 36 observations, taken at random from this population, exceeds 78 is:
- If n samples are extracted from any population with mean value [img=11x18]1803dc1a4012523.png[/img] and variance [img=18x22]1803dc1a48a9511.png[/img], then A: When n is sufficiently large, the distribution of sample mean is approximately normal distribution. B: When n<10, the distribution of sample mean is approximately normal distribution. C: The distribution of sample mean is nothing to do with n. D: No matter how big n is, the distribution of the sample mean is not going to be close to a normal distribution.
- When measuring the dispersion of the sample mean, the statistics to be used are ( ) . A: Coefficient of variation B: The standard deviation C: Standard deviation of the mean D: Range value
- Which of the following about the normal distribution is NOT true? A: Theoretically, the mean, median, and mode are the same B: About 68% of the observations fall within ±1 standard deviation from the mean C: Its parameters are the mean, μ, and standard deviation, σ D: It is a discrete probability distribution.
内容
- 0
As a general rule, the normal distribution is used to approximate the sampling distribution of the sample mean only if
- 1
The difference between the sample mean and the population mean is called the: A: population deviation. B: population standard deviation. C: standard error of the mean. D: sampling error.
- 2
The difference between the sample mean and the population mean is called the sampling error.
- 3
Which of the following is true about the sampling distribution of the sample mean? A: The mean of the sampling distribution is always μ. B: The standard deviation of the sampling distribution is always σ. C: The shape of the sampling distribution is always approximately normal. D: D) All the alternatives are correct
- 4
2.Which of the following about the normal distribution is NOT true A: Theoretically, the mean, median, and mode are the same. B: About 2/3 of the observations fall within ±1 standard deviation from the mean. C: It is a discrete probability distribution. D: Its parameters are the mean, μ, and standard deviation, σ.