#### Answer

2.7 N

#### Work Step by Step

Coulomb’s law shows us that the magnitude of the force between charges is inversely proportional to the square of the distance between them.
If the separation distance is multiplied by a factor of $\frac{1}{8}$, the force is multiplied by a factor of 64.
$$F_{new}=64(4.2\times10^{-2}N)=2.7N$$