SOLUTION: Thirty-five items are randomly selected from a population of 370 items. The sample mean is 34, and the sample standard deviation 8. Develop a 90% confidence interval for the popula

Algebra ->  Probability-and-statistics -> SOLUTION: Thirty-five items are randomly selected from a population of 370 items. The sample mean is 34, and the sample standard deviation 8. Develop a 90% confidence interval for the popula      Log On


   



Question 1069138: Thirty-five items are randomly selected from a population of 370 items. The sample mean is 34, and the sample standard deviation 8. Develop a 90% confidence interval for the population mean.
It tells me to round every answer to 3 decimals, and to round the final answer to 2 decimals. I keep getting 33.31 to 34.96, and it tells me its wrong. Help please

Answer by MathTherapy(10556) About Me  (Show Source):
You can put this solution on YOUR website!
Thirty-five items are randomly selected from a population of 370 items. The sample mean is 34, and the sample standard deviation 8. Develop a 90% confidence interval for the population mean.
It tells me to round every answer to 3 decimals, and to round the final answer to 2 decimals. I keep getting 33.31 to 34.96, and it tells me its wrong. Help please
Confidence interval:   x -  E   <   µ   <     x  +   E, where:

x = sample mean (34, in this case)
E (Margin of Error) = Zα/2   *   s%5Bx%5D%2Fsqrt%28n%29
Zα/2 = Ƶ-critical score, based on 90% confidence level (1.645, in this case)
S%5Bx%5D = Sample standard deviation (8, in this case)
n = sample amount (35, in this case) 

                   x -  E   <   µ   <  x  +   E   then becomes: 
34+-+1.645+%2A+%288%2Fsqrt%2835%29%29   <   µ   <   34+%2B+1.645+%2A+%288%2Fsqrt%2835%29%29
           34 – 2.224  <   µ   <  34  +  2.224 
                 31.776  <   µ   <  36.224