average hourly in standard error of the mean is a. 1.611 C. .8083. d. 80.83 In order to estimate the average electric usage per month, a sample of 81 houses was selected and the electric usage was determined. Assume a population standard deviation of 450 kilowatt-hours. At 95% confidence, the size of the margin of error is O a. 50.00 b. 98.00 C.1.96 d. 42.00 A random sample of 25 employees of a local company has been taken. A 95% confidence interval estimate for the mean systolic blood pressure for all employees of the company is 123 to 139 Which of the following statements is valid? a, 95% of the population of employees has a systolic blood pressure between 123 and 139. O b, 95% of the sample of employees has a systolic blood pressure between 123 and 139 O c. If the sampling procedure were repeated many times, 95% of the sample means would be between 123 and 139. d. If the sampling procedure were repeated many times, 95% of the resulting confidence intervals would contain the population means sto ic blood (O pressure Hide Feedback Incorrect a. Degrees of freedom b. Margin of error C. Mean d. Standard deviation Hide Feedback Incorrect In order to estimate the average electric usage per month, a sample of 81 houses was selected and the electric usage was determined. Assume a population standard deviation of 450 kilowatt-hours. At 95% confidence, the size of the margin of error is a. 50.00. b. 98.00. C. 1.96 d. 42.00. Hide Feedback Incorrect