I am trying to solve a problem algebraically rather than trying to use real numbers to try and avoid gaining misleading result due to assuming values incorrectly. In doing this, a problem has arisen that I cant figure out and would appreciate some help please?

The question is:

"If the current flowing through a resistor falls to half its original value, the power will.. :"

a. Double

b. Decrease by 4 times

c. Halve

d. Increase by 4 times

In case my workings are not as clear as I hope, my confusion is that I am getting two different outcomes :/

OUTCOMES

P2 = P1 / 2 (i.e power would halve) AND

P2 = P1 / 4 (i.e. power would decrease by 4 times)

I've been told that the correct answer is B) that the power would decrease by four times. I did get this as one of my outcomes, but I also have got an incorrect outcome, hence there is something going on with my maths (or something???) and I'm not sure what. I cant see what's wrong with the

P2= P1/2 logic - but clearly this is incorrect.

Please help!?

The only thing that I can think of is that with the

P2= P1/2 equation ,

this was formulated involving voltage. There is no mention of voltage in the question, possibly making it an 'unreliable' factor to involve at all?

I know when I originally tackled this problem, I tried to solve it using real numbers and P=VI. As there was no mention of voltage I tried just to kept voltage constant. But doing this, the answer I yielded was that the power halved (when current halved). Again, it was incorrect, again the result was that the power would halve. Same wrong answer. Both approaches to solving the problem involved voltage. Is this what's gone wrong? If so is that a rule?

It just seems like a big margin of error when a 'true' equation can be incorrect. Which makes me think that I am messing it up. Please help if you can see what I'm doing wrong?

Thanks heaps !