AP EAMCET Engineering 26 Apr 2017 Shift 1 Paper

The half life of a stream of radioactive particles moving along a straight path with a constant kinetic energy of 4 eV is 1 minute. The percentage of particles which decay before travelling a distance of 3.6 km is______________.
(Mass of the radioactive particles = 3.2×10−21kg and charge of the electron = 1.6×10−19 C)