Answer: 12663.3 cubic inches sand is needed for this sandbox.
Explanation:
Formula : Volume of cuboid = Base area x height
Volume of sandbox = 1146 x 13 = 14898 cubic inches
Quantity of sand required to fill = 85% of Volume of sandbox
= 0.85 x 14898 [85% = 0.85 ]
= 12663.3 cubic inches
Hence, 12663.3 cubic inches sand is needed for this sandbox.