An ion with a mass m and a magnitude of charge of 1e is initially at rest when it is accelerated by a potential difference of magnitude δv. after exiting the accelerating potential, it enters a region with a uniform magnetic field perpendicular to the ion's velocity. the ion moves in a semicircle of radius r. next, an ion with a mass m'and a magnitude of charge of 4e is accelerated by the same potential difference and deflected by the same magnetic field. the radius of its semicircular path is r' = 3r. find the ratio of the ion masses, m'/m.

m'/m = ?