# Electric field strength -- calculating distance from charge

## Homework Statement

At a distance D from a very long (essentially infinite) uniform line of charge, the electric field strength is 1000 N/C. At what distance from the line will the field strength to be 4000 N/C?

E=kq/r2

## The Attempt at a Solution

I know that E is inversely proportional like so: E~1/r2
hence by rearranging for 'r' I got: r~sqrt(1/E)
then I plugged in 4E because 4000 N/C is four times 1000 N/C: r~sqrt(q/4E)
and I got r~E/2 but the answer is E/4 and I don't know how?

BvU