To determine the weight of a 1/2-inch thick steel plate with dimensions 8 feet by 4 feet, we can follow these steps:
1. Identify the weight per square foot for a 1/2-inch steel plate:
- It is a standard value that a 1/2-inch thick steel plate weighs 20 lbs per square foot.
2. Calculate the area of the steel plate:
- The plate has dimensions of 8 feet in length and 4 feet in width.
- The area [tex]\( \text{Area} \)[/tex] in square feet is:
[tex]\[
\text{Area} = \text{Length} \times \text{Width} = 8 \, \text{ft} \times 4 \, \text{ft} = 32 \, \text{sq ft}
\][/tex]
3. Determine the total weight in pounds:
- Since the weight per square foot is 20 lbs, the total weight [tex]\( \text{Total Weight} \)[/tex] in pounds is:
[tex]\[
\text{Total Weight} = \text{Area} \times \text{Weight per Square Foot} = 32 \, \text{sq ft} \times 20 \, \text{lbs/sq ft} = 640 \, \text{lbs}
\][/tex]
4. Convert the weight to kilograms:
- The conversion factor from pounds to kilograms is approximately 1 lb = 0.453592 kg.
- Thus, the total weight in kilograms [tex]\( \text{Total Weight in kg} \)[/tex] is:
[tex]\[
\text{Total Weight in kg} = 640 \, \text{lbs} \times 0.453592 \, \text{kg/lb} \approx 290.3 \, \text{kg}
\][/tex]
Therefore, the weight of a 1/2-inch steel plate that is 8 ft x 4 ft is 640 lbs (290.3 kg).
Thus, the correct answer from the provided options is:
640 lbs (290.3 kg).
