What is the Equivalent Capacitance in This Circuit?

[Acuben]

Homework Statement

http://yfrog.com/mrcapdg

http://img819.imageshack.us/img819/1172/capd.th.gif

Find equivalent capacitance
answer is 4C/3

Homework Equations

whatever is in parenthesis is subscript
formula1: series: 1/C(eq)= 1/C(1) + 1/C(2) + 1/C(3) + ...
formula2: parallel: C(eq)=C(1)+C(2)+...

formula3: V=Q/C

The Attempt at a Solution

because of symmetry I decided that 3C has 0 charge (0q) and that top part has same voltage as the bottom part

charge split top and bottom equally

so I solved the problem "as if" 3C doesn't exist
so on the top series I get C/3 (using formula 1) and C/3 for bottom as well since it's in symmetry
and top and bottom form parallel so I get
2C/3 using formula 2

which is only half the answer

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[rl.bhat]

For top branch 1/Ceff = 1/C + 1/2C = ?

 

[Acuben]

o thanks for pointing that out, I made simple algebra mistake ^^