Question 105718
The pitfall here is in thinking that you need 4 cuts to make 4 pieces.  You really need 3 cuts to make 4 pieces.  Think about it, if you have one log and you make one cut, you know have two pieces of log.  So, if you need to make 3 cuts and it takes you 12 seconds to do this, each cut takes:

12 seconds / 3 cuts = 4 seconds per cut

Now, to cut a similar log into 5 pieces would require 4 cuts at 3 seconds for each cut or:

4 cuts * 4 seconds/cut = 16 seconds.