The yearly average solar flux incident on a horizontal surface in the United States is about 200 W/m2. The average total energy demand in the United States is approximately 100 quads (100 10^18 J) per year. Assuming an average efficiency of PV cells of 14% and a biomass conversion efficiency around 1%, estimate the percentage of land required to provide the energy of the country by these two renewable technologies, respectively. (The total land area of the United States is about 9.2 10^6 km2 ) (if you don't know biomass conversion, you can treat it as another "PV" at the efficiency of 2%).