Wang's Concrete Service notes that the number of jobs each month follows the following distribution: 10 with probability 0.15, 11 with probability 0.20, 12 with probability 0.20, 13 with probability 0.20, 14 with probability 0.15, and 15 with probability 0.10. The probability that a specific job will be for a residential driveway is 70%, and the probability that it will be for a commercial project is 30%. Revenues for residential driveways follow a normal distribution, with a mean of $500 and a standard deviation of $50. Commercial projects, although more lucrative, also have larger variability. Wang estimates that revenues here follow a normal distribution, with a mean of $1,500 and a standard deviation of $400. Set up a simulation model for Wang's problem and replicate it N times to calculate the average monthly revenue.