I will explain it for you.
To find the volume of a cube you will need to do:
side x side x side
For a rectangular prism you will need to do:
length x width x height
For a cylinder you will need to do :
pie x radius*2 x height
You are trying to solve a rectangular prism so you will need to do :
9.5 x 15 x 13 = 1852.5 cubic inches
I hope my explanation will help you with your problem. :)