Answer:
749 lbs
Explanation:
weight of the water in the mattress = volume of the mattress x weight of water
volume of the mattress = volume of a cuboid = length x width x height
6 x 2 x 1 = 12 ft³
weight of the water in the mattress = 12 x 62.4 = 748.8 lbs
749 lbs to the nearest pound