Question

The exponential function N = 500 × 0.74t, where t is measured in years, shows the amount, in grams, of a certain radioactive substance present.
What is the monthly percentage decay rate? (Round your answer to one decimal place.)
%

(d) What is the percentage decay rate per second? (Note: For this calculation, you will need to use all the decimal places that your calculator can show. Round your answer to eight decimal places.)
%

Answer 1

since there are 12 months, the monthly decay factor is 0.74^(1/12) = 0.9752
That is a 2.48% monthly decline

Now do the same logic, using the fact that there are 365.25*86400 seconds in a year. Better use an online calculator which will give you more than 10 digits of precision.