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ex2_fa06asol

ex2_fa06asol - STA 6126 Fall 2006 Exam 2 PRINT Name A...

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STA 6126 Fall 2006 Exam 2 PRINT Name ____________ A research article conducts a significance test to determine whether the mean food expenditures differ among families in two societies. Their 95% Confidence Interval for μ 2 1 is (32 , 48). Which of these statements best describes the P-value for testing H 0 : μ 2 1 = 0 vs H A μ 2 1 0: a) P-value < 0.05 (Equivalence of CI and 2-sided test) b) P-value 0.95 c) P-Value 0.05 d) We need more information to obtain the P-value Two graduate students obtain individual random samples of members of the Graduate Student Union at their large university. They ask each sampled student whether they favor a candidate for the president of their union. Satchel samples 100 students, of which 45 favor the candidate. Lee samples 200 students, of which 110 favor the candidate. Whose 95% confidence interval for the true proportion of all graduate students will be narrower (more precise) ? Why? Assume that the university has over 10,000 graduate students so that the sample sizes are negligible relative to the population. a) Satchel’s because of a lower sample size b) Satchel’s because of a lower proportion c) Lee’s because of a higher sample size (see formula for std error) d) Lee’s because of a higher proportion e) They will be the same, since .45(1-.55) = .55(1-.45) For a large-sample test of H 0 : μ = 0 vs H A : μ < 0, the z -test statistic is 0.40. Give the P-value: a) .8446 b) .6554 (P(z)<.40, lower tailed test) c) .6892 d) .3446 A study is being conducted to determine whether a new formulation of whitening

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ex2_fa06asol - STA 6126 Fall 2006 Exam 2 PRINT Name A...

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