The problem statement has a problem with it, since it states that the current source is ideal, but then specifies an other-than-infinite output resistance, meaning that it is a non-ideal current source. Just like the voltage source is non-ideal because it has an other-then-zero output resistance. To resolve this, the most reasonable thing to do is assume that the problem statement has a typo and it meant to state that the current source was non-ideal.

You need to show your best attempt to work the problem as far as you can, we can then help you either identify where you are going astray, or guide you a bit further down a good path.

The good news is that one of the offered answers is correct (sadly, that's not always the case).

 

The problem statement has a problem with it, since it states that the current source is ideal, but then specifies an other-than-infinite output resistance, meaning that it is a non-ideal current source. Just like the voltage source is non-ideal because it has an other-then-zero output resistance. To resolve this, the most reasonable thing to do is assume that the problem statement has a typo and it meant to state that the current source was non-ideal.

You need to show your best attempt to work the problem as far as you can, we can then help you either identify where you are going astray, or guide you a bit further down a good path.

The good news is that one of the offered answers is correct (sadly, that's not always the case).

Is it 49.5 ?

I connected a series resistance of 1k to the voltage source and a parallel resistance of 9 k to the current source. Simple source transformation let me determine that a current of 55 Amps flows through a net resistance of 0.9k which gives 49.5V wrt reference

I had assumed 9k in series with the current source which was, I think, my mistake.

 

Is it 49.5 ?

I connected a series resistance of 1k to the voltage source and a parallel resistance of 9 k to the current source. Simple source transformation let me determine that a current of 55 Amps flows through a net resistance of 0.9k which gives 49.5V wrt reference

I had assumed 9k in series with the current source which was, I think, my mistake.

That is correct. Putting the output resistance of a non-ideal current source in series with an ideal current source is a common mistake. It's also one that you can avoid by developing the habit of always asking if what you are doing makes sense.

What happens if you have a resistance in series with an ideal current source and you put a black box around it? From the outside, absolutely nothing will happen. Since it is in series and since an ideal current source will push it's output current through whatever is connected to it, you will still have the current coming out of the terminals of the box. The ideal source will just be producing more voltage, but that is something that is hidden from the outside by the box.