A Random Sample of 85 Group Leaders, Supervisors, and Similar

Multiple Choice

A random sample of 85 group leaders, supervisors, and similar personnel revealed that on the average a person spent 6.5 years on the job before being promoted. The standard deviation of the sample was 1.7 years. What is the 95% confidence interval for the true population mean?

A) 6.46 and 6.54
B) 3.17 and 9.83
C) 6.13 and 6.87
D) 6.20 and 6.70
E) 6.32 and 6.88