Sand added to a container

Question

Jack placed a rectangular box into a rectangular container.  The rectangular box is 15 cm long, 10 cm wide and 10 cm high.  The rectangular container is 30 cm long 20 cm wide and 15 cm high.  Jack filled the box with sand to a depth of 7cm and filled the container with sand to a depth of 10cm.   How much sand did he use in all?

Answer 1

This is a volume question.

 

Calculate the volume of the container (filled to a depth of 10 cm.).

Subtract the volume of the box (in its empty state, because it's buried in the sand).

Add the volume of sand that was placed into the box.