At the site of a spill of radioactive iodine, radiation levels were four times the maximum acceptable limit, so an evacuation was ordered. If R₀ is the initial radiation level (at t = 0) and t is the time in hours, the radiation level R(t), in millirems/hour, is given by R(t) = R₀(0.996)^t.

(a) How long does it take for the site to reach the acceptable level of radiation of 0.6 millirems/hour?

(b) How much total radiation (in millirems) has been emitted by that time?