Historical data indicated that the time required to service the conveyor belt at Coca-Cola Amatil's Richlands operations can be modelled as a normal...

Historical data indicated that the time required to service the conveyor belt at Coca-Cola Amatil's Richlands operations can be modelled as a normal distribution with a standard deviation of 18.2 minutes. A random sample of 23 services revealed a mean service duration of 76.6 minutes. Determine a 90% confidence interval for the mean service time in minutes. State the lower bound of this interval correct to two decimal places.