An accounting firm is planning for the next tax preparatinseason. From last year's returns, the firm collects asystematic random sample of 100 filings. The 100 filingsshowed an average preparation time of 90 minutes with a standarddeviation of 140 minutes. What is the probability that the mean completion time isbetween 1 and 2 hours, i.e., 60 and 120 minutes? A. Approximately 1 B. 0.1664 C. 0.8336 D. 0.9675 An accounting firm is planning for the next tax preparatinseason. From last year's returns, the firm collects asystematic random sample of 100 filings. The 100 filingsshowed an average preparation time of 90 minutes with a standarddeviation of 140 minutes. What is the probability that the mean completion time isbetween 1 and 2 hours, i.e., 60 and 120 minutes? A. Approximately 1 B. 0.1664 C. 0.8336 D. 0.9675
Explanation / Answer
z = (60-90)/(140/(100)) = -2.14 ==> P(z P(z< 2.14) =0.9838 0.9838 - 0.0162 = 0.9676 ==> ANSWER IS D