stat quiz 7

stat quiz 7 -...

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Xenylopaline group is 72.7 and the sample standard deviation is 18.0. The mean score for the placebo  group is 56.2 and the sample standard deviation is 12.4. The psychologists would like to construct a 95% confidence interval for the difference between population  mean score for Xenylopaline takers (μ 1 ) and the population mean score for non Xenylopaline takers (μ 2 ) in  this attention span test. When doing this, the psychologists assume that the variation in scores is the same  for both populations. The following  Student's t distribution table  may assist you in answering the following  questions. a) Calculate the lower bound of the confidence interval. Give your answer to 3 decimal places. Lower bound =  b) Calculate the upper bound of the confidence interval. Give your answer to 3 decimal places. Upper bound =  [0 out of 2] -    Feedback a) This is not correct. Lower bound =  10.359 b) This is not correct. Upper bound =  22.641 Calculation Note that this confidence interval will involve a pooled-variance because the psychologists are assuming  that the population variances are equal. The pooled variance can be calculated using the following formula:  show variables s p 2 = (n 1 - 1)s 1 2 + (n 2 - 1)s 2 2 (n 1 - 1) + (n 2 - 1) = (43 - 1) × 18.0 2 + (54 - 1) × 12.4 2 (43 - 1) + (54 - 1) = 229.024
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a) The lower bound can be calculated using the following formula:  show variables L = (x 1 - x 2 ) - t * (s p 2 (1/n 1 + 1/n 2 )) ½ = (72.7 - 56.2) - 1.9853 × (229.024 × (1/43 + 1/54)) ½ = 10.35925024. .. = 10.35 9 Rounded as last step b) The upper bound can be calculated using the following formula:  show variables U = (x 1 - x 2 ) + t * (s p 2 (1/n 1 + 1/n 2 )) ½ = (72.7 - 56.2) + 1.9853 × (229.024 × (1/43 + 1/54)) ½ = 22.64074976. .. = 22.64 1 Rounded as last step -  2 of 3   ID: MST.CP.CTM.02.0010
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Fantra is interested in comparing the average age of its consumers in two cities (city 1 and city 2) so that it  can decide whether different advertizing campaigns are required for each city. A random sample  of 38 people were selected from each city and their ages were recorded. The mean age for the first city was  calculated as 19 years. The mean age for the second city was calculated as 22years. It is known that the  population standard deviation of the ages of Fantra consumers is 3 years in both cities. You may find this  standard normal table  useful throughout the following questions. a)
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stat quiz 7 -...

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