Question

How much of a sample will be left after 3 half-lives?

Answer 1

In half life the number of the sample will reduce to 50% of therir initial number.

So after first half life, sample remained will be 50%.

`100*(50)/(100)=50`

After second half life 50% of the remaing sample will again disintegrate, so we are left with 25% of the sample.

`50*(50)/(100)=25`

After third half life the 50% of the remaining sample will again disintegrate so we are left with only,

`25*(50)/(100)=12.5`

So after 3 half life only 12.5% of the sample will be remaining.