James Desreumaux, VP of Human Resources of American First Banks (AFB), is reviewing the employee training programs of AFB.His staff randomly selected personnel files for 100 tellers in the southeast region and determined that their mean training time was 25 hours.Assume that the population standard deviation is 5 hours.The 92% confidence interval for the population mean of training times is ________.
A)16.25 to 33.75
B)24.30 to 25.71
C)17.95 to 32.05
D)24.12 to 25.88
E)24.45 to 27.32

Question

Quizplus · Accepted Answer

To calculate the 92% confidence interval for the population mean, we use the formula for the confidence interval: mean ± (Z * (σ/√n)), where mean = 25 hours, σ (population standard deviation) = 5 hours, n = 100, and Z is the Z-score corresponding to the 92% confidence level. Looking up the Z-score for 92% confidence level gives us approximately 1.75. Plugging these values into the formula gives us 25 ± (1.75 * (5/√100)) = 25 ± 0.875, which results in the interval 24.12 to 25.88.