After a spill of radioactive iodine, measurements showed the ambient radiation levels at the site of the spill to be four times the maximum acceptable limit. the level of radiation from the iodine source decreases according to the formula: r(t) = r0e-0.004twhere r is the radiation level (in millirems/hour) at time in t hours and r0 is the initial radiation level (at t=0).
a) how long will it take for the site to reach an acceptable level of radiation?
b) how much total radiation (in millirems) will have been emitted by that time, assuming the maximum acceptable limit is 0.6 millirems/hour?