STAT 301 REVIEW FOR EXAM 2 ANSWERS 1 2 3 4 a and d a c e 5 B F Test 6 A z CI 7 D F Test 8 A t Test 9 C t Test 10 E t CI 11 D F Test 12 C t CI 13 A t CI 14 A z Test 15 a Yes n 15 so t test is fine unless you have strong skewness or outliers of which we have none We do not know the population standard deviation b H 0 200 c d e f H a 200 t 11 119 P value 0 df 15 Reject H 0 and conclude that there is enough evidence to show that the high risk group s population average cholesterol level is significantly higher than 200 mg dl 233 65 249 60 230 63 252 66 16 a 1 285 4 840 b H0 diff 0 where diff before after H0 diff 0 t 3 672 p value 0 002 2 0 001 Reject H 0 and conclude that there is enough evidence to show that the medication significantly improves lowers cholesterol levels in the population c No because you can only use a CI to test two sided significance tests 17 a H 0 1 2 H a 1 2 b t 4 069 and P value 0 001 1 c Reject H 0 there is enough evidence to conclude that there is a significant difference in the population average weights of the combs of roosters fed two different vitamin supplement diets d 9 25955 56 02616 18 a Matched pairs b H 0 y x 0 versus H a y x 0 Also ok to use diff with diff y x but not ok to use y x c t 2 378 x 0 85 d t D sD 1 5852 20 n e 0 014 f Reject H 0 there is enough evidence to show that the new breakfast drink tastes significantly better than the old breakfast drink on average in the population 19 a H 0 10 6 H 0 10 6 b Z 2 00 c P value 0228 d Fail to reject H 0 at alpha 0 01 level There is not enough evidence to show that the new fertilizer produces a population mean yield significantly above 10 6 bushels acre e Picture 20 a 59 21 64 37 b 2 578 c H 0 61 3 H a 61 3 Since 61 3 is in the confidence interval you fail to reject H 0 and conclude that there is not enough evidence to show that the population mean weight of male runners is significantly different from 61 3 21 a There is a significant difference between the distance the 2005 titanium and the other two drivers can hit b 7 689 2 10 799 so yes c 9 71 d 0 7256 e H 0 1 2 3 H a at least one i is different F 43 626 P value 0 2 Reject H 0 at least one driver has a different population mean from the others f No you need Bonferroni s procedure Bonferroni s procedure found a significant difference between the 2005 titanium and the other two drivers The steel and the persimmon drivers are not significantly different 22 a The driver type affects distance since none of the lines are horizontal the ball type affects distance since all of the lines are not on top of each other and the interaction is significant since the lines are not parallel b The main effects of driver and ball are significant and interaction is significant to population mean drive distance 23 C 24 B 25 D 26 D 27 B 28 A 29 D 30 a 2 b 4 c 2 31 C 32 C 33 Picture with 2 tails shaded with the total representing the P value lines drawn at t 3 138 and t 3 138 34 D 35 E 36 Picture with line drawn at t 3 138 whole curve to the left of this line is shaded representing the P value 37 B 38 D 2 independent groups with 1 quantitative variable 39 C 1 sample with everybody tested twice before and after 40 A 1 quantitative variable from 1 sample population standard deviation known 41 B 1 quantitative variable from 1 sample population standard deviation unknown 42 E more than 2 independent groups divided up one way by race 1 quantitative measurement 43 F 2 categorical ways of dividing up the subjects race and weight gain 1 quantitative measurement 3
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