1. The problem statement, all variables and given/known data http://img339.imageshack.us/my.php?image=45979944dp2.jpg 2. Relevant equations Why did the 10 ohm resistor turn into a 5 ohm resistor when we make it an open circuit. This is not a homework question, it was an example problem given to us to help prepare for our midterm. 3. The attempt at a solution Normally, when I try and find my Th and Norton equivalents, there is a voltage. Deactivating the sources doesn't change any of the values (in the problems i've done). When Solving something like I would find Req and then apply current division. Afterwards I can apply ohm's law to find Vth. However, it doesn't work out to the answer i am supposed to get because of how the resistor changed. Can someone explain to me why this is happening? Or is it simply a typo?