Electric Field Calc: Determine Magnitude w/ Spreadsheets/Calculus

[formulajoe]

using calculus, spreadsheet techniques or mathcad, determine the magnitude fo the electric field for the capacitor along the line parallel to and equidistant from both of your lines of charge.

what we did was place aluminum ink on a conductive paper. we applied 15 volts to one strip and grounded the other. we measured the voltage along a line between the center of the lines of charge.
i want to use spreadsheet techniques to do this, but the way its looking i don't have the correct information. can i use a line straight down the center of the cap to find the magnitude of the electric field with calculus or spreadsheets? if so, how do i do either? just looking for some direction.

 

[formulajoe]

i think I've got an idea of how to do this. use the integral of dE, which equals the integral of [k*(Q/L)*dY]/r^2. or some similar equation, if i keep changing the test point it should give me what i want if i average. correct?

 

[formulajoe]

okay, i think I've got the equation set. but it requires Q. i don't know how to find Q. Q will be the charge on the sides of the cap. all i have is the voltage and distance