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?
举一反三
- Let X be a normal random variable with mean 20 and standard deviation 4. The 90th percentile of X is ____________.
- 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?
- 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.
- 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: