A population of 10 cargo aircraft each produces a profitof 4,000 per 24-hour period when not waiting to be unloaded. Thetime between arrivals is distributed exponentially with a mean of144 hours. The unloading time at the ramp is distributedexponentially with a mean of 18 hours. It costs150 per hour tolease a ramp with this unloading capacity. How many ramps should beleased?