A scientist begins with 100 milligrams of a radioactive substance that decays exponentially. After 36 hours, 50 mg of the substance remains. How many milligrams will remain after 52 hours ?

It is easy to calculate the half-life as 36 hours.

Looking at the graphic, we see that we will need the bottom formula

Ending Amount = Beginning Amount / 2^n

Where "n" is the number of half-lives which = 52 hours / 36 hours = 1.4444444 half-lives.

Ending Amount = 100 mg / 2^1.444444444

Ending Amount = 100 / 2.71258

Ending Amount = 36.74336230689

or rounding that off, it's about 36.743 milligrams

Step-by-step explanation: