Statistical Analysis Homework Solutions: Confidence Intervals and Hypothesis Testing, Assignments of Statistics

Download Statistical Analysis Homework Solutions: Confidence Intervals and Hypothesis Testing and more Assignments Statistics in PDF only on Docsity! Homework 5 Solutions 1) For the mean OC level, the 95% confidence interval is 33.4 ± (1.96)(19.6/√31 ) = 33.4 ± 6.90 = 26.50 to 40.30 ng/ml. 2) For the mean monthly rent for unfurnished one-bedroom apartments in Boston, the 95% confidence interval is $1400 ± (1.96)($220/√10 ) = $1400 ± $136.36 = $1263.64 to $1536.36. 3) (a) The standard deviation of the mean is σx = 3.5 20 = 0.7826 mpg. (b) For the mean fuel efficiency, the 95% confidence interval is 43.17 ± (1.96)(3.5/√20) = 43.17 ± 1.5339 = 41.6361 to 44.7039 mpg. 4) (a) [137.8, 148.2] (b) The interval gets smaller. (c) The interval gets bigger. 5) If the presence of pig skulls were not an indication of wealth, then differences similar to those observed in this study would occur less than 1% of the time by chance. 6) For testing these hypotheses, we find z = 10.2−8.9 2.5 6 = 1.27. This is not significant (P = 0.1020); there is not enough evidence to conclude that these sonnets were not written by our poet. (That is, we cannot reject H0.) 7) (a) H0: μ = 9.5 mg/dl vs. Ha: μ ≠ 9.5 mg/dl.