Question

The half-life of a substance is 15 hours. After 60 hours, how much of a 800-gram sample remains?

Answer 1

this one's easy because 60 is a whole multiple of 15. How many half-lives will pass over 60 hours if each half-life is 15 hours?

If half of the sample decays over every half-life, each next half-life will take half of what's left from the last time.

\[\frac{800g}{1}*\frac{1}{2}*\frac{1}{2}*\frac{1}{2}*\frac{1}{2} = ?\]where each \(\frac{1}{2}\) is the passing of one half-life