Each cube below is 1 cm on a side.

1. Based on the pattern, find the volume of Figure III.

   Hint (a):

   What is the difference between Figure (II) and Figure (IV)?

   

2. If the pattern continues, write an expression to represent the volume of figure N. What kind of sequence is this?

   Hint (b):

   Find the common difference between the volumes of each figure.

   Answer (b):

   $4n − 3$, arithmetic