week 2 e-text scott ward

week 2 e-text scott ward - o Chapter Exercises 9.54 Faced...

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o Chapter Exercises 9.54 Faced with rising fax costs, a firm issued a guideline that transmissions of 10 pages or more should be sent by 2-day mail instead. Exceptions are allowed, but they want the average to be 10 or below. The firm examined 35 randomly chosen fax transmissions during the next year, yielding a sample mean of 14.44 with a standard deviation of 4.45 pages. (a) At the .01 level of significance, is the true mean greater than 10? H 0 = 10 H 1 > 10 a = .01 T = (14.44-10) / (4.45 / sqrt(35)) = 5.903 Dof = 34 a = .01 CV = 2.33 Yes the true mean is greater than 10. (b) Use Excel to find the right-tail p-value. X = 5.903 Dof = n – 1 = 35 – 1 = 34 Tails = 1 o Chapter Exercises 9.56 A coin was flipped 60 times and came up heads 38 times. (a) At the .10 level of significance, is the coin biased toward heads? Show your decision rule and calculations. Heads = 38/60 = 19/30 H 0 : p = 0.5 H 1 : p > 0.5 Z = (0.633 - 0.5) / sqrt(.5 x .5 / 60) = 2.066 (b) Calculate a p -value and interpret it. =1-NORMDIST(0.6333,0.5,SQRT(0.5*0.5/60),1) P = 0.019 It is safe to say that the coin is biased to heads.
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o Chapter Exercises 9.62 The Web-based company Oh Baby! Gifts
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