An accounting firm is planning for the next tax preparation season. From last year's returns, the firm collects a systematic random sample of 100 filings. The 100 filings showed an average preparation time of 85 minutes with a standard deviation of 135 minutes. What is the probability that the mean completion time is between 1 and 2 hours, i.e., 64 and 121 minutes?
0.9368
0.4981
Approximately 1
0.9962