How Do I Calculate Theoretical Charge and Discharge Times in RC Circuits?

[d_sx]

I've been set the following assignment on RC circuits that I thought I understood. Turns out I don't:

http://www.geocities.com/danielessex/images/electronicsmain.jpg

I understand what is happening in the circuit and what it is asking me to do but I don't really know how to go about it.

When i transposed the charging formula i got:
t=ln(1-Vc/V0)x-RC

When i transposed the discharging formula i got:
t=ln(Vc/V0)xRC

Not really sure if these are correct but if they are, how do I go about calculating the theoretical charge and discharge times when I don't know Vc

I might just be being stupid but Maths and Physics were never my strong points so any help would be much appreciated (or if you want to do the assignment I wouldn't mind ;P)

Thanks for you time and help,
Dan - Edinburgh, Scotland

 

[d_sx]

Just like to say thanks for the 'overwhelming' response from you all.!

Thanks a bunch!

 

[Brad Barker]

well, I'm not sure about everyone else, but the document in your first link is unreadable on my computer.