Solving Q=Q0(e^(-t/RC)): Need Help for Part C

[flyers]

Homework Statement

2. Homework Equations

Q= Q₀(e^(-t/RC))

The Attempt at a Solution

I need help for part C.I am confused as to what value I should put for R.

The answer is supposed to be .166 seconds

 

[Mindscrape]

R2 and R3 are in series when the switch opens. Did you get parts a) and b) right?

Find when Q=.25*Q0

 

[flyers]

I was confused because I thought R2 R3 were connected in parallel, but I see why they are in series now. Thanks