Basic question on resistance

[Gregg]

1. The problem statement, all variables and given/known data
http://www.ocr.org.uk/Data/publications/past_papers_2005_june/L_AS_Level_Physics_A_2822_Jun_2005_Question_paper. pdf

Question 5


2. Relevant equations



3. The attempt at a solution

For a) I put that because the circuit isn't closed there's no current.

for b) I can see that the total resistance would be the sum of
168k\Omega + R_2

R = \frac{V}{I}
R = \frac{3.4}{I}

I don't know the current. I'm new to this so I don't really know how to solve. I think an example would help.

[nucleus]

You have enough information to get current across the resistor.