The force exerted by the wind on a plane surface varies jointly with the square of the velocity of the wind and with the area of the plane surface. If the area of the surface is 20 square feet surface and the wind velocity is 30 miles per hour, the resulting force is 10 pounds. Find the force, F, on a surface of 75 square feet with a velocity of 40 miles per hour. (Round your answer to two decimal places.)