I've posted theorem-related questions on this newsgroup that are honest (ungraded homework problems) and don't plan to dishonor a take-home examination that deals with all the theorems. But a question on an examination regarding maximum power transfer, which I answered, or attempted to answer, by thevenizing the circuit gave a Rth with a decimal. I doubt its accuracy for that reason. Barring the fact that this *is* a "make-believe" classroom question employing Thevinin's Theorem, am I wrong in being concerned that my Rth has a value with a decimal? (Don't answer if you think I'm wrong for asking this or feel free to tell me I shouldn't be asking.) Second, our instructor asked for the Efficiency of the circuit once we found the value of the load. I assume, because he and the textbook claim it, that the value of the load must equal Rth. He also asked for the Power of the load; and, using P(out)/P(in), I arrived at an infinitesmal difference. I employed the equations he did for computing Efficiency--i.e., Pout/Pin, or (according to him) I^2 x R(load)/Eth x I. Since this is a maximum power transfer question, am I wrong in assuming the proportion of the value of the numerator to the denominator *must* be 2:1 to arrive at an efficiency rating of 50%? Thanks in advance for any responses and apologies if I stated any of this in an uninformed or crude way.