Electrical circuits: when all switches are closed, what is R?

[GreenTea09]

Homework Statement

https://pasteboard.co/Hj3g5Km.jpg

When both switches 1 and 2 are closed,what is the total resistance of the set up? I couldn't figure out which resistors are connected in parallel and which resistors are actually in series in this set up when both swtiches are closed. I trace back to the original current source to see if there is any splitting of the current at each section and there is, and from there i conclude they are all connected in parallel and the attempt at my solution is to calculate the total resistance of the resistors as if they are all connected in parallel. My final results in 7.5 Ohms. According to answer sheet, the correct answer should be 2.5 Ohms. The problem lies in my parallel/series circuit identification. Can anyone please advise which resistors are connected in parallel or series?

Homework Equations

1/R(T) = 1/R1 + 1/R2 + 1/R3 + 1/R4

The Attempt at a Solution

https://pasteboard.co/Hj3gtIW.jpg

 

[CWatters]

Look carefully at what S1 does to the left hand resistor, and what S2 does to the right-hand resistor.

 

[anorlunda]

Hint: What happens in a circuit when a wire is in parallel with a resistor?