Question

3) On March 11, 2011, a massive earthquake and tsunami triggered a major disaster at Japan's Fukushima nuclear plant. A plume extending to the northwest of the site deposited significant

amounts of iodine-131, cesium-134, and cesium-137 up to 30 miles away. iodine-131 has an 8-day half-life and cesium-137 has a 3-year half-life. How long will it take for 99% of the iodine-131 and 99% of the cesium-137 to naturally decay according to first order kinetics?

Fig: 1