According to the Air Transport Association of America, the average operating cost of an MD-80 jet airliner is $2.270 per hour. Suppose the operating costs of an MD-BQ jet airliner are normally distributed with a standard deviation of $173 per hour. (Round the volue of z to 2 dedmal places, es. 12.5. Round your answers to 2 decimol ploces es. 125.31.) (a) At what operating cost woudd only 20% of the operating costs be less? (b) At what operating cost would 6576 of the operating costs be more? (c) What operating cost would be more than BSic of operatineconts?.