Hi there!
Recall the equation for the electric field produced by a point charge:
[tex]E = \frac{kQ}{r^2}[/tex]
E = Electric field (2.86 × 10⁵ N/C)
k = Coulomb's Constant (8.99 × 10⁹ Nm²/C²)
Q = Charge (3 × 10⁻⁶ C)
r = distance from center of charge (? m)
Rearrange the equation to solve for 'r'.
[tex]r^2 = \frac{kQ}{E}\\\\r = \sqrt\frac{kQ}{E}}}\\\\r = \sqrt{\frac{(8.99\times10^9)(3\times10^6)}{(2.86\times 10^5)}} = \boxed{0.307 m}[/tex]
