A radioactive isotope has a half life of T years. How long will it take the activity to reduce to `3.125%`.

a radioactive isotope has a half life of T years. how long will it take the activity to reduce 1% of its original value.

The half-life of a radioactive element is 1580 years. How long will it take to reduce to 1/4th of its original mass ?

A radioactive substance has an averge life of 5 hours. In a time of 5 hours the decay in percentage is