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(c) Now suppose that you pick a sample of 25 cars, what is the probability that the sample mean will exceed 77 mph? Does CLT applies? explain? 5.- In a sample of 200 men, 100 admitted to driving without a seat belt. In a sample of 150 women, 60 admitted to driving without a seat belt. At α = 0.05, is there a diﬀerence in the proportions of men and women driving without a seat belt?(Both Methods) 2014-03-27 21:34:07 3/8 M_150_t_2_r_fa_13_h.pdf (3/8) 6.- A Special Forces Military Recruiter claims that the height his recruits have a standard deviation of 3inches. A sample of 20 of its recruits find that the sample standard deviation is 3.5inches. At α = 0.01, is there enough evidence to support the his claim (Do both methods, this is a two tailed test)? 2014-03-27 21:34:07 4/8 M_150_t_2_r_fa_13_h.pdf (4/8) 7.- Apple claims that the battery life of the iPhone is better than that of the Google phone. A sample is taken from each company. The Apple sample (n = 26) had a mean of 10hours and standard deviation of 1hour, while the Google sample (n = 28) had a mean of 9hours with a standard deviation of 2hours. (a) Is there a diﬀerence in the battery life of the two companies? Use α = 0.01 (Both Methods) 2014-03-27 21:34:08 5/8 M_150_t_2_r_fa_13_h.pdf (5/8) 8.- A new volley-ball shoe manufacturer claims that its shoes increase the vertical jump (in inches) of any athlete. The following tables shows that result of five athletes with regular shoes and the new shoes. Is there enough evidence to suggest that there is a diﬀerence? Use α = 0.05. Table 1: Vertical Jumps in Inches x1 30 28 27 33 x2 34 29 27 34 2014-03-27 21:34:08 6/8 M_150_t_2_r_fa_13_h.pdf (6/8) 9.- Consider the following data. x 2 3 5 6 9 y 15 15 10 8 3 -x2 - -y 2 - -xy- (a) Find r (b) Find ŷ (c) Predict y when x is 4. 2014-03-27 21:34:08 7/8 M_150_t_2_r_fa_13_h.pdf (7/8) Contingency Tables Step 1 H0 : The row and column variables are Independent Ha : The row and column variables are Dependent Step 2 2 χ ∗= ! (E − O)2 , E E= (row sum) · (column sum) total sum Step 3 Find the Rejection Region or P-value Step 4 Conclusion Ex: An instructor wishes to see if the way people obtain information is independent of the educational background. A survey of high school and college graduates yielded this information. at α = 0.05, test the claim that the way people obtain information is independent of their educational background. - T.V Newspaper Other High School 150 90 50 College 40 40 30