# The half life of the radioactive element Strontium-90 is 37 years. In 1950, 15 kilograms of this element released accidentally. How do you determine the formula which shows the mass remaining after t years?

##### 1 Answer

Note: The half life of Strontium-90 is now published as **28.8 years**. This will require adjustments of all the following values in

#### Explanation:

The formula for the half life of an **exponentially** decaying substance is:

To calculate the mass of Strontium-90 remaining after

For example

In 2017 (now) the amount left is