# If the half life of a radioactive substance is 4 days. Calculate the time required to decrease the concentration of 1/8th of original??

##### 1 Answer

Half life of a radioactive substance is defined as the time taken for it to degrade to 1/2 of its original quantity.

I like looking at the problem this way

So it reaches

The time required, therefore, to decrease the concentration of 1/8th of original would be

**Now, this is the formula approach.**

Let