You wish to determine the electric field magnitude along the perpendicular bisector of a 260-mm line along which 35 nC of charge is distributed uniformly. You want to get by with a minimal amount of work, so you need to know when it is sufficient to approximate the line of charge as a charged particle. At what distance along the perpendicular bisector does your error in E reach  4% when you use this approximation? Express your answer to two significant digits and include the appropriate units.