Surface Charge Density and electric field

[PatrickGeddes]

Homework Statement

A nonconducting wall carries charge with a uniform density of 8.55 µC/cm2.
(a) What is the electric field 8.55 cm in front of the wall if 8.55 cm is small compared with the dimensions of the wall?

Homework Equations

σ= Q/A
E=σ/2Eo

The Attempt at a Solution

E=8.55/2 x 8.854x10^-12

 

[PatrickGeddes]

Don't think this is right, I feel like the factor that the 8.55cm from the wall should make a difference. Is that right?