举一反三
- 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:
- 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:
- A researcher wants to estimate the proportion of the population which possess a given characteristic. A random sample of size 600 is taken resulting in 330 items which possess the characteristic. The point estimate for this population proportion 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?
- If we are interested in testing whether the proportion of items in population 1 is larger than the proportion of items in population 2, then
内容
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A researcher decide to draw the entire sample from one "representative" city, and the population includes all cities. the researcher must be confident that the chosen sample is truly representative of the entire population. This is belonging to ().
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A point estimator will be unbiased if the A: expected value of the point estimator equals the value of the population parameter B: sample size is greater than 30 or np ³ 5 and n(1-p) ³ 5 C: sampling distribution is normally distributed D: value of the population parameter is known
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which statement is right? A: We can observe the entire population. B: A sample drawn from the population of interest. is not adequate to discribe population. C: In the Monte Carlo demonstration from last time, an individual dataset was the sample and the Data Generating Process described the population. D: none of the above is right
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The proportion of the English in the whole population accounts for .
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A summary measure that is computed from a sample to describe a characteristic of the population is called: