Solving Force of Charges Problem - 1nC Charge in Middle

[cemar.]

Homework Statement

What is the force F on the 1nC charge in the middle due to the four other harges? Give your answer in component form.

There is a picture that i don't know how to get up so ill just describe it.

There are four charges in a square, length of square = 1cm. the two charges on the left corners of the square are -2nC and the two charges on the right corners of the square are +2nC. There is a charge in the middle of the square of +1 nC.

Homework Equations

I'm just using F= (kq1q2/r^2)

The Attempt at a Solution

so what I am doing is a force diagram and from that i know that the y components cancel out. the magnitude of the forces is equal, therefore their x components will be equal. Using the force equation under step two i determined the magnitude of the force and from that was able to determine the x component with cosine and a 45 degree angle. I then multiplied the x component by 4.
The answer i ended up with was 5.1E-4 where the real answer is actually double that.

Thanks!

 

[Shooting Star]

The concept is correct. There must have been some arithmetical mistake somewhere. Show your calculations briefly.