What is the total resistance in the given circuit?

[Gregg]

Homework Statement

http://www.ocr.org.uk/Data/publications/past_papers_2005_june/L_AS_Level_Physics_A_2822_Jun_2005_Question_paper.pdf

Question 5

Homework Equations

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.