You are given the following information about a dry-batch paving operations. You are going to use one mixer that has a service rate of 30 services per hour. The dry-batch trucks you use for bringing concrete to the paver have an arrival rate of 7.5 arrivals per jour. Each truck carries 6cu yd of concrete. You have a total amount of 13,500 cu yd of concrete to pour. You rent a truck at $15 per hour, and the paver at $60 per hour. If the job takes more than 80 hours, you pay a penalty of $140 per hpur owing to delays in job completion. On the basis of least cost, determinate the number of trucks you should use. Plot the cost versus the number of trucks used.