The hall-life for the radioactive decay of Ce-141 is 32.5 days. If a sample has an activity of 3.9 uCi after 195 d have elapsed, what was the initial activity, in microcuries, of the sample?
Express your answer using two significant figures.

The yearly amounts of carbon emissions from cars in belgium are normally distributed with a mean of 13.9 gigagrams per year and a standard deviation of 5.8 gigagrams per year. find the probability that the amount of carbon emissions from cars in belgium for a randomly selected year are between 11.5 gigagrams and 14.0 gigagrams per year. a. 0.340 b. 0.660 c. 0.167 d. 0.397