Let X be a normal random variable with mean 20 and standard deviation 4. The 90th percentile of X is ____________.
25.126
举一反三
- Suppose X is a normal random variable with mean 60 and standard deviation 2. A z-score was calculated for a number, and the z-score is 3.4. What is x?
- 中国大学MOOC: A population distribution is normal with a mean of 18 and standard deviation of 4. A sample of 16 observations is selected and a sample mean computed. What is the probability that the sample mean is more than 18?
- 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.
- 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:
- 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.
内容
- 0
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
- 1
The standard error of the mean is never larger than the standard deviation of the population.
- 2
The function f(x) that defines the probability distribution of a continuous random variable X is a:
- 3
B1型题 表示正态分布的资料中数据的离散程度最常用的指标为（） A: mean B: vanance C: percentile D: standard deviation E: coefficient of variation
- 4
Presenting as mean ± standard deviation, the results were analyzed with SPSS 23.