# PSY your problems answered a+ - 10. For A population has a...

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2. Describe the distribution of sample mean (shape, expected value, and standard error) for samples of n =36 selected from a population with a mean of u= 100 and a standard deviation of o = 12. By the central limit theorem we know that the sample mean Xbarwill be approximately normal with the mean of the random variableX, μ, and standard deviation σ/√n. for avalue of n=36 the approximation will be excellent. Hence Xbar will be bell-shaped with μ=100 andσ xbar =12/6=2 (which is it's standard error). 6.For a population with a mean of 50 and a standard deviation of 10 how much error on average would you expect between the sample mean M and the population mean for: a) a sample of n = 4 scores b) a sample of n = 16 scores c) a sample of n = 25 scores as the sample size increase we will expect the mean of the sample to be closer and closer to 100. even with the smallest sample we expect the mean to be near 100.

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Unformatted text preview: 10. For A population has a mean of u = 60 and a standard deviation of o = 24. Find the z score corresponding to each of the following samples: a. M= 63 for a sample of n = 16 scores b. M= 63 for a sample of n =36 scores c. M= 63 for a sample of n = 36 scores the z-scores are (M - ) / (/sqrt(n)) a) (63-60)/(24/sqrt(16)) = 1/2 b) (63-60)/(24/sqrt(36))=3/4 c) (63-60)/(24/sqrt(64))=3/3=1 14. The population of IQ scores forms a normal distribution with a mean of h = 100 and a standard deviation with a mean of 0 = 15. What is the probability of obtaining a sample mean greater than M =105, a. for a random sample of n = 9 people? b. for a random sample of n = 36 people? z = (x - )/(/n) (a) z = (105 - 100)/(15/9) = 1 20.A normal shaped distribution u=80 and tau=15. a)sketch the distribution of sample means for samples of n = 25 scores from this population u=80 tau=15/sqrt n = 15/5 = 3...
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## This note was uploaded on 05/10/2011 for the course STATS 202 taught by Professor Emil during the Spring '11 term at Aberystwyth University.

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PSY your problems answered a+ - 10. For A population has a...

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