# The half-life of Tungsten-181 is 121 days. If you start with 3 pounds of it, how much do you have after 7 years?

##### 1 Answer

May 7, 2018

#### Explanation:

Convert the number of years into days so that we can determine how many half-lives have passed.

7 years=

Use the equation:

Hence, as the initial mass is 3 pounds and the number of half-lives is 21.13: