4. Calculate the beam and total radiation tilt factors and the beam and total radiation incident on a surface tilted at 45° toward the equator one hour after local solar noon on April 15. The surface is located at 40 °N latitude and the ground reflectance is 0.25. For that day, the beam radiation on a horizontal surface is GB = 710 W/m², and then diffuse radiation on the horizontal is GD = 250 W/m².