# Question #dbed0

##### 1 Answer

Aug 11, 2017

#### Answer:

The mass left after

#### Explanation:

The half life is

This means that half the amount present at time

The radioactive constant is

We can solve this problem with the equation

The radioactive constant is

The initial mass is

Therefore, the mass left after

Now,

The mass left is

We apply the same equation

The time is