What is the magnitude of the electric field?

1. The problem statement, all variables and given/known data
What is the magnitude of the electric field in the region between the plates?
The charge on the sphere is 5.00 mC
The image needed to visualize situation:
http://www.webassign.net/userimages/66097?db=v4net
mass of sphere = 3.2grams
2. Relevant equations
F = EQ
Fg = mg



3. The attempt at a solution
First, I drew a free body diagram. Tension went up along the thread, Fg (gravity) was pointing down at the electrical force was pointing to the right. I then solved for Fg, which I got .03136N from multiplying (9.8)(.0032). I then set Ft(tension) * cos30 = .03136, which I then got Ft = .0362114089. I then plugged my Ft, multiplied it by sin30 in order to get the electrical force, which turned out to be .0181057044. From there, I used the equation F=EQ, which I did (.0181057044)(5e-3), which i then ended up with 3.621140888 N/C which was obviously the wrong answer.
 

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