I was given the following question on a homework assignment dealing with op-amps. "Given an input of 0.1V DC with a gain of 10 and a common mode voltage of 0.009, what is the common mode output with a CMRR of 70dB? What is the total output voltage?" So far, the only thing I have been able to calculate is the common mode gain, which has gotten me nowhere. I'm not even sure that part is correct, as I assume the gain of 10 the instructor gave us is a closed loop gain, and I was under the impression that open-loop gain was used in the following equation: CMRR=20log(differential V gain/CM gain) 70 =20log(10/CM gain) 3.5 =log(10/CM gain) 10(to 3.5 power) =(10/CM gain) CMgain=10/10(to3.5) =0.0032 I have spent hours researching this question and am obviously missing something. Can anyone please help me figure out where I went wrong? Thanks!!