1. Convert the dimensions of the sheet to inches:
   • Longitud: 4 feet = 48 polzades
   • Amplada: 8 feet = 96 polzades
2. Convert the thickness to decimal form:
   • 3/16 polzada = 0.1875 polzades
3. Calculate the area of the sheet in square inches:
   • Àrea = Longitud x Amplada = 48 inches x 96 inches = 4,608 square inches
4. Calculate the volume of the sheet in cubic inches:
   • Volum = Àrea x Gruix = 4,608 square inches x 0.1875 inches = 864 cubic inches
5. Convert the volume from cubic inches to cubic feet:
   • Volum (cubic feet) = Volume (cubic inches) / 1728 = 864 cubic inches / 1728 = 0.5 cubic feet
6. Determine the density of aluminum. The density of aluminum is typically around 0.098 lliures per polzada cúbica.
7. Multiply the volume in cubic feet by the density to calculate the weight in pounds:
   • Pes (lliures) = Volume (cubic feet) x Density = 0.5 cubic feet x 0.098 lbs/in³ ≈ 0.049 lliures

Per tant, a 4×8 3/16 xapa d'alumini would weigh approximately 0.049 lliures.