Compute the effective radiation dosage (in Sieverts) for a 67kg person who is exposed to 6.9*10^9 particles of alpa radition. Presume that 77% of the radiation is absorbed, each alpha particle has an energy of 6.6*10^-13 J, and that the RBE of the alpha particles is 15. Note that RBE is sometimes call the quality factor, abbreviated as Q.