Question

The annual earnings of the population vacance randomly selected computer schware engineers have a sample standard deviation of $3009. Assume the sample is from a normal distributed population Construct a confidence interval for and the population standard deviations. Use a level of confidence interpret the results What is the confidence for the population are ? (Round to the nearest integer as needed) Interpret the rest. See the correct choice below and Round to the nearest Integer as needed) in the answer boxes) to complete your choice OB. With 10% confidence, you can say that the population variance is less than OA With 10% confidence, you can say that the population variance is between and OC. With 90% confidence, you can say that the population vacances between OD With SON confidence, you can say that the population variance is greater than What is the confidence interval for the population standard deviation ? C o und to the rest eger as needed) in the answer bo Interpret the results Select the correct choice below and (Round to the nearest integer as needed) l o complete your choice Click to select your answers

Answer 1

Excel add-in (PH Stat) procedure: Step 1: In EXCEL, Select Add-Ins > PH Stat > Confidence Intervals > Estimate for the Population Variance Step 2: In Data, enter 14 as the Sample size, 3609 as the Sample Standard deviation, and 90% as the Confidence Level. Step 3: Click OK Excel add-in (PH Stat) output:

Confidence Interval Estimate for the Population Variance T Data Sample Size Sample Standard Deviation Confidence Level 14 3609 90% Intermediate Calculations Degrees of Freedom Sum of Squares Single Tail Area Lower Chi-Square Value Upper Chi-Square Value 13 169323453 0.05 5.8919 22.3620 Results Interval Lower Limit for Variance Interval Upper Limit for Variance 7571916.9546 28738518.4754 Interval Lower Limit for Standard Deviation Interval Upper Limit for Standard Deviation 2751.7116 5360.8319 The 90% confidence interval for the population variance o2 is (7571917, 28738519). C. With 90% confidence, you can say that the population variance is between 7571917 and 28738519.

The 90% confidence interval for the population variance ois (2752, 5361).