Applying linearity in a circuit

[rms5643]

Homework Statement

Find Io in the network in the figure below using linearity and the assumption that Io = 1 mA.
Figure:http://i.imgur.com/Xtu0VmG.jpg

Homework Equations

KCL, KVL, basic analysis techniques.

The Attempt at a Solution

The following values I have calculated correctly:
VR1=9V
VR2=61V
VR3=70V
I1=1mA
I2=2mA
VR4=138V
VS=208v
I3=??
IS=??
IoActual=??

So, my trouble lies in finding I3, as once I find I3, I can easily find IS using KCL, though, the current source is doing something to the voltage drop across I3 that I'm not understanding.

How I tried to solve for I3 was the same way I solved for VS. Since the voltage drop across the source is 208v, then I assumed that the voltage drop across the two resistors on the left summed to 208v as well.

So, using Ohms Law: V/R=I, 208v/(42000Ω+26000Ω)=3mA, which is incorrect. Where did I go wrong?

Thank you

 

[vela]

Rounding errors probably. Your analysis is fine. Just use fractions instead of calculating decimals and rounding.

 

[rms5643]

Rounding errors probably. Your analysis is fine. Just use fractions instead of calculating decimals and rounding.

Thank you very much Vela. You were correct. 3mA was incorrect, but 3.05mA was correct. (My online homework has a +/- 2% tolerance, so 0.5 was enough to fall outside of the threshold!

Thanks for verifying my methodology.