Answer:
We can use Coulomb's law to solve this problem:
F = k * q1 * q2 / r^2
where F is the force between the two charges, k is Coulomb's constant (k = 9 x 10^9 N m^2 / C^2), q1 and q2 are the magnitudes of the charges, and r is the distance between them.
We know the force F, the distance r, and the magnitude of one of the charges q1. We can rearrange the equation to solve for the magnitude of the other charge q2:
q2 = F * r^2 / (k * q1)
Substituting the values we have:
q2 = (250 N) * (0.15 m)^2 / (9 x 10^9 N m^2 / C^2 * 6.5 x 10^-5 C)
Simplifying:
q2 = 8.65 x 10^5 C
Therefore, the magnitude of the other charge is 8.65 x 10^5 C.