The dimensions of the sandbox are 5.2 ft, 4 ft, and 1.5 feet.
The volume is
5.2*4*1.5 = 31.2 ft³
One-third of the volume is
31.2/3 = 10.4 ft³
One cubic foot of sand sells for $1.30. The cost to fill one-third of the sandbox is
(1.30 $/ft³)*(10.4 ft³) = $13.52
Answer: $13.52
