SP07A_EC41_F09

# SP07A_EC41_F09 - EC 41; UCLA; Sample Problems #7A Chapters...

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EC 41; UCLA; Sample Problems #7A Chapters 6 & 7 1) SAT exam scores vary normally with true mean μ (unknown) and standard deviation σ = 100. What is the 90% Confidence Interval for the mean test score implied by a sample of 10,000 students with a sample mean X = 478? 2) Consider the SAT exam scores above ( σ = 100). a) Calculate the p-value for the test of H 0 : μ = 475, versus H A : μ > 475 for a sample of 10,000 students with sample mean X = 478. b) Is the test in 2a significant at the 5% level of significance? Suppose you are told a difference of 3 points on the SAT does not affect the chance of admission much – can this be correct? Is it possible for a difference to be statistically significant but not of practical importance? Briefly explain relating your answer to the size of n and σ . 3) Bottles of Spud are supposed to contain 350 ml of beer but sometimes the bottling machinery malfunctions and less than 350 ml is in each bottle on average. The standard deviation per bottle σ = 8 ml. even when the machinery malfunctions. a) Write down the null and alternate hypothesis regarding the mean amount of beer per bottle. Compute z calculated (the “z test statistic”) for a sample of 16 bottles with a mean = 347. b) Compute the relevant p-value. Is this for a one or two sided test? Do we reject or accept the null hypothesis at the 5% level of significance? 4)

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## This note was uploaded on 04/29/2010 for the course ECON 41 taught by Professor Guggenberger during the Spring '07 term at UCLA.

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SP07A_EC41_F09 - EC 41; UCLA; Sample Problems #7A Chapters...

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