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Exam 7: The Distribution of Sample Means

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Question 1

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A sample is obtained from a population with σ = 20.If the sample mean has a standard error of 5 points, then the sample size is n = 4.

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Question 2

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The distribution of sample means ____ .

A) is always a normal distribution.
B) will be normal only if the population distribution is normal.
C) will be normal only if the sample size is at least n = 30.
D) we be normal if either the population is normal or the sample size is n > 30.

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Question 3

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A sample from a population with μ = 40 and σ = 10 has a mean of M = 44.If the sample mean corresponds to a z = 2.00, then how many scores are in the sample?

A sample obtained from a population with σ = 12 has a standard error of 2 points.How many scores are in the sample?

A sample of n = 25 scores is selected from a population with μ = 70 and σ = 20.It is very unlikely that the sample mean will be smaller than 72.

If the sample size is equal to the population standard deviation (n = $\sigma$ ), then the standard error for the sample mean is equal to 1.00.

What term is used to identify the mean of the distribution of sample means?

Under what circumstances will the distribution of sample means be normal?

What happens to the standard error of M as sample size increases?

The mean for a sample of n = 4 scores has a standard error σ = 5 points.This sample was selected from a population with a standard deviation of σ = 20.

For a normal population with a mean of µ = 80 and a standard deviation of σ = 10, what is the probability of obtaining a sample mean greater than M = 75 for a sample of n = 25 scores?

For a particular population a sample of n = 4 scores has an expected value of 10.For the same population, a sample of n = 25 scores would have an expected value of _____.

According to the central limit theorem, the standard error for a sample mean becomes smaller as the sample size increases.

A sample of n = 9 scores is selected from a normal population with a mean of µ = 80 and a standard deviation of σ = 12.The probability that the sample mean will be greater than M = 86 is equal to the probability of obtaining a z-score greater than z = 1.50

If samples are selected from a normal population, the distribution of sample means will also be normal.

A sample of n = 9 scores is randomly selected from a population with µ = 80 and σ = 9.If the sample mean is M = 83, then the corresponding z?score is z = +3.00.

For a normal population with µ = 40 and σ = 10 which of the following samples is least likely to be obtained?

A sample of n = 100 scores is selected from a population with μ = 80 with σ = 20.On average, how much error is expected between the sample mean and the population mean?

A sample of n = 4 scores is selected from a population with μ = 30 and σ = 8.The probability of obtaining a sample mean greater than 34 is equal to the probability of obtaining a z-score greater than z = 2.00 from a normal distribution.

The mean for a sample of n = 9 scores has a standard error of 2 points.This sample was selected from a population with a standard deviation of σ = 18.