13.7. The number of fires occurring during a 24-hour day follows a Poisson distribu- tion with a mean of 4 fires per day as shown in the accompanying table. In examining past records, the fire chief finds that 75 percent of all fires require only one truck and the amount of time required to extinguish a fire is normally distributed with a mean of 3 hours and a standard deviation of 0.5 hour. The other 25 percent of reported fires required 2 trucks and the time to put them out is normally distributed with a mean of 4 hours and a standard deviation of 1 hour. Assume the district has 10 trucks and use a simulation sample of 10 days to determine the average daily utilization of trucks.