Final answer:
The water in the king-size waterbed mattress weighs approximately 1491 pounds.
Step-by-step explanation:
To find the weight of the water in the king-size waterbed mattress, we first need to convert the measurements to the same units. The depth is given in inches, so we need to convert it to feet by dividing by 12. The dimensions of the mattress are 5.5 feet by 6.5 feet by 8/12 feet.
To find the volume of water, we multiply the dimensions together: 5.5 ft * 6.5 ft * 8/12 ft = 23.92 ft³.
Since water has a density of 62.4 pounds per cubic foot, we can calculate the weight of the water in the mattress by multiplying the volume by the density: 23.92 ft³ * 62.4 lb/ft³ = 1490.85 lb.
Therefore, the water in the king-size waterbed mattress weighs approximately 1491 pounds.