Stats Air operates a daily flight between Melbourne and Coffs Harbour that has operated for three years. Flight XZ 912 is scheduled to depart Melbourne at 12:00 and arrive in Coffs Harbour at 13:50. Flight XZ 913 is scheduled to depart Coffs Harbour at 14:35 and arrive in Melbourne at 16:25. Both flights XZ 912 and XZ 913 are scheduled to take 110 minutes. Of course, often the two flights depart or arrive earlier or later than scheduled. Flights XZ 912 and XZ 913 use the same aeroplane: It goes from Melbourne to Coffs Harbour and then back. Note that Melbourne and Coffs Harbour are always in the same time zone. Hao is interested in the amount of time it takes for the aircraft to complete the entire sequence, that is, to fly to Coffs Harbour, complete a turn-around at Coffs Harbour airport and then fly back to Melbourne. According to the flight schedule, the entire sequence should take 265 minutes. He randomly selects 49 days in the past three years and records the number of minutes between the time when flight XZ 912 departs Melbourne and the time when flight XZ 913 arrives in Coffs Harbour. He found that the average of those times was 289.42 minutes and the standard deviation of those times was 17.5 minutes. Compute the 86% confidence interval for the true mean number of minutes for the aircraft to complete the sequence. Lower endpoint : Upper endpoint : (Give your answer correct to at least 5 significant figures) (Give your answer correct to at least 5 significant figures)