Odine-131 has a half-life of 8.04 days. How many grams of a 500 g sample will remain after 35 days? Round your answer to the nearest hundredth of a gram.

35/8.04=4.353234 approx. So there are this many half-life periods. The iodine sample halves its size for every period. So we need to calculate 0.5 to this power=0.0489 approx. Multiply this by 500=24.46g.