Exponential Decay - Example
Problem: A radioactive isotope of iodine decays exponentially. There is 50 mg of the element initially, 35 mg after 4 days.
(a) Find a formula of the form
(b) Find the half-life, , of the isotope.
Finding is easy: is the initial amount at . Indeed, . Hence, , and our formula must be
Now we have to find k .