### Solution:

Let the dimensions of the first rectangular box be:First Box:

Height = x

Width = y

Length = z

Volume of this rectangular box is given by substituting these values in the formula:

Volume of cuboid = Length X Breadth X Height

Volume = xyz = 10 cubic feet

Second box:

Height = 2x(twice as long as the first box)

Width = 2y (twice as wide as the first box)

Length = 2z(twice as high as the first box)

Volume = We know, xyz = 10 cubic feet

Therefore, the capacity, in cubic feet, of the second sandbox is 80 cubic feet.

So, option 3 is correct.