Nair,Rejesh-Exam3 (1) - Problem 1 2 3 4 5 6 7 8 Earned 12...

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Problem Value Earned 1 12 12 2 12 12 3 12 12 4 12 12 5 12 12 6 12 12 7 13 13 8 15 15 Total 100 100 1) In new housing developments, it is sometimes difficult to get utilities (water, electricity, natural gas) installed in a timely fashion. Your firm is considering investing in a new development which can finish housing construction in 90 days. A random sample of the times (in days) from the request for service connection to the time of service completion yielded the following data: 114 78 96 125 150 103 117 113 86 99 114 110 104 73 86 Is this data consistent with the hypothesis that on average it takes 90 days from request to connection of utility service? Use the 5% level of significance. Answer MEAN 104.53 STD DEVIATION 19.66 SIZE 15 ALPHA 5% i.e 0.05 Hypothesis Definition: Ho: mu = 90 Ha: mu != 90 Template for Confidence Interval Sample Sample Sample Mean SD n alpha Enter ===> 104.53 19.66 15 0.05 Confidence Interval is 93.64 to 115.42
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Since 90 does not lie between the confidence interval. we reject the null hypothesis The data is not consistent with the hypothesis that on average it takes 90 days from r On average it takes 93.64346 to 115.4232 days from request to connection of utility se
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request to connection of utility service ervice
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2) An auditor for a government agency is assigned the task of evaluating reimbursement for office visits to doctors paid by Medicare. The audit is to be conducted for all Medicare payments in a specific geographical area during a certain month. In that area and for that month there were so many visits that the number is too large to process in a timely manner. Accordingly, the auditor decides to take a random sample from these visits. She wishes to estimate ther average Medicare payment to within $5.00 with a confidence of 95%. How large a sample should she take? In a preliminary sample of size 30, she found that the standard deviation of Medicare payments was $34.42. Answer For 95% confidence interval we take z = 1.96 Preliminary sample Sample Size = 30 Sample Std.Dev s = 34.42 Desired Width W = 5 n >= 182.05 Approximately 183 Result Approximately we need 183 random observations. Since we already took 30 observat To get a good result we need 183 observations.
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tions we need 183-30 = 153 observations more.
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3) The marketing branch of the Mexican Tourist Office would like to increase the proportion of tourists who purchase silver jewelry while vactioning in Mexico from its present value of 40%. Toward this end, promotional literature describing both the beauty and value of the jewlery is prepared and distributed to all passengers on airplanes arriving at a certain seaside resort during a one week period. A random sample of 500 returning passengers was selected and it was found that 240 had purchased silver jewelry while in Mexico. Does this provide evidence that the promotional campaign
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Nair,Rejesh-Exam3 (1) - Problem 1 2 3 4 5 6 7 8 Earned 12...

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