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1) Z=(9.98-10)/(0.03/sqrt(3) = -1.15 2) (16.5-25.7)+-2.39*sqrt(41.785/36+41.785/36) = ( -12.84, -5.56) 3) Cannot do not normal 4) DF SS MS Groups 2 8.6402 4.321 Error 9 1.6128 1792 Total 11 10.253 5) .02/2=1.282*sqrt(.3(1-.3)/n) N=3451.4 Need 3452 emails F 24.108 6) H0: Hair color and eye color are independent Ha: Hair color and eye color are dependent Exp Brown Blue Green 2 Hours 5 Hours 7 Hours 22.1 19.1 17.7 24 20.8 19.2 28.8 25.0 23.1 χ24 = 7.412 Partial Brown Chi^2 2 0.37 Hours 5 1.042 Hours 7 2.15 Hours Blue Green 0.07 0.16 1.62 0.03 1.94 0.03 .1 < P-value < .15 Therefore Fail to Reject the null Which means there is not sufficient evidence to prove that beam color and fire resistance are dependent 7) 0.02<p-value<0.04 8) H0: proportions are equal (not cheating) Ha: proportions are not equal (is cheating) Alpha = 0.05 18 20 18 14 32 50 38 44 z 1.439 38 38 38 38 32 32 32 32 1 1 1 1 82 82 82 82 82 82 82 82 32 50 38 44 18 20 14.83 23.17 0.678 0.434 14 30 17.17 23.83 0.5852 0.3747 X21=2.072 p-value = 0.0749 0.10<p-value<0.15 Fail to Reject We cannot say my daughter is cheating 9) (14-15) +- 2.998*1.22/sqrt(8) = (-2.29, 0.293) 10) H0: B1=0 Ha: B1≠0 α=0.05 t5=-1.02/0.246 = -4.15 2*.0025<p-value<2*0.005 0.005<p-value<0.01 Reject Heavier cars do not carry the same amount of Freon 11) H0: mu >=2 Ha: mu < 2 Type 1 error: The batteries will last, but we think they will die (lose money) Type 2 error: The batteries will not last, but we think they will (no calculator during test) Personally I would raise alpha, maybe 0.20 because I don’t want my calculator to die during the exam, and this would make it more likely that I am going to replace them (even if I don’t need to) 12) ______ 95% of the time confidence intervals like this capture the true average time between a felony ______ We are 95% confident the true average is between 2.3 and 5.7 seconds 13) H0:μ≤1 Ha:μ>1 α=0.05 Note that “Error” refers to how far off from 2 1.9 1.02 1.98 2.46 x 1.84 4 s t3 1.9 1.842 1.02 1.842 1.98 1.842 2.46 1.842 4 1 0.6 1.84 1 2.8 0.6 4 0.025<p-value<0.05 Reject the null The average error from the scale is significantly more than 1, which means the scale needs to be replaced 14) 9 said do the homework 7 said enjoy the songs 5 said take good notes 4 said study with classmates 4 said don’t use the book 3 said attend class 2 said go back over the homework 2 said get help when you need it 2 said start the homework early Other responses: Put confidence intervals on your study sheet Learn the language of statistics Pay attention to the wording and context of the questions Make a flow chart Go to office hours Make a good study sheet for the exam Study hard Pay attention in class It’s not that hard Do the practice exams Don’t do the homework all on one day Don’t work 30 hours and take 15 credits Use engineering paper Beware the final! Don’t forget everything on the final Everyone hates statistics. Just do better than the next guy and get it over with You’ll never get an A in this class Run! The instructor is insane and possibly dangerous. Quit this silliness and join the college of business Dr. Crawford is a thug and he don’t take no crap. Don’t give him crap. Good luck roll Tide Statistics is like a garden. Dig it