Phosphorous-32 is a radioactive isotope used to mark cells in biological experiments. The isotope has
a daily decay rate of 4.85%. Suppose that a certain experiment begins with 40 micrograms of
phosphorous-32.
a) Write a formula for the amount of isotope A (in µg) that remains t days after the experiment
begins.
b) How much of the isotope remains after 5 days?
c) How long will it take for the amount of the isotope that remains to fall to 10 µg?
