A straight semicircular tunnel with a width of 20 feet is carved into a mountain. The curved walls are to be painted white and the flat roadway is to be paved with asphalt. If one barrel of white paint can cover 40 square feet and an equal number of barrels of paint and barrels of asphalt are used, how many square feet must one barrel of asphalt cover?




1) Pi/4

2) 10 Pi

3) 80/Pi

4) 2

5) Cannot be determined from the information given