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Homework 04 - Answers and Points

# Homework 04 - Answers and Points - HomeworkAssignment4...

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Psychology 60 Spring 2010 Homework Assignment 4 1) For a population with μ = 50, and σ = 10, find the standard error, σ X , when: a. (1 point) n = 4, σ X = σ n = 10 4 = 10 2 = 5 b. (1 point) n = 25, σ X = σ n = 10 25 = 10 5 = 2 c. (1 point) n = 100, σ X = σ n = 10 100 = 10 10 = 1 2) (2 point) The distribution of sample means is not always distributed normally. Under what circumstances will the distribution of sample means not be normal? The distribution of the sample means will be non-normal if the population is non-normal and the sample size is smaller than about 35. 3) For a population with σ = 20: a. (1 point) How large a sample would be needed to have a standard error less than 10 points? σ X < 10, σ n , 20 n n > 4 b. (1 point) How large a sample would be needed to have a standard error less than 4 points? σ X < 4, σ n , 20 n n > 25 c. (1 point) How large a sample would be needed to have a standard error less than 2 points? σ X < 2, σ n , 20 n n > 100 4) A population has a mean of μ = 100 and a standard deviation of σ = 20. Find the z‐score for each of the following sample means obtained from this population: a. (1 point) X = 102 for sample of 4 scores z X = X μ σ X , z X = 102 100 σ / n , z X = 102 100 20 / 4 , z X = 2 10 = 0.2 b. (1 point) X = 102 for sample of 100 scores z X = X μ σ X , z X = 102 100 σ / n , z X = 102 100 20 / 100 , z X = 2 2 =

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Homework 04 - Answers and Points - HomeworkAssignment4...

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