Answer
$F = 2.4\times 10^{-16}~N$
Work Step by Step
We can find the magnitude of the electric field:
$F = \vert q \vert~E$
$E = \frac{F}{\vert q \vert}$
$E = \frac{3.0\times 10^{-6}~N}{2.0\times 10^{-9}~C}$
$E = 1500~N/C$
We can find the magnitude of the force on a proton:
$F = q~E$
$F = (1.6\times 10^{-19}~C)(1500~N/C)$
$F = 2.4\times 10^{-16}~N$
