# The half-life of cobalt-60 is 5.26 years. If 50 g are left after 15.8 years, how many grams were in the original sample?

##### 1 Answer

Jul 3, 2016

#### Answer:

#### Explanation:

The following formula relates the mass remaining of the radioiosotope to the original mass:

Where:

First, find the number of periods.

Then plug in the values in the original formula

A quick approach

Knowing that the time represents three periods