A 458 Winchester magnum cartridge has a 500-grain (1gr=.0648g) bullet that attains a muzzle speed of 644.9 m/s. After traveling 456m, it would still…

A 458 Winchester magnum cartridge has a 500-grain (1gr=.0648g) bullet that attains a muzzle speed of 644.9 m/s. After traveling 456m, it would still be moving at 365.6 m/s. What fraction of its original KE does it have at that distance?