The capital investment cost for a switchgrass-fueled ethanol plant with a capacity of 200,000 gallons per year is $3.2 million. The costcapacity factor for this particular plant technology is 0.59 for capacities ranging from 150,000 gallons per year to 500,000 gallons per year. What is the estimated capital investment for a similar ethanol plant with a capacity of 450,000 gallons per year? The estimated capital investment for a similar ethanol plant with a capacity of 450,000 gallons per year is $ (Round to the nearest ten thousands.)