A 100 ml solution of a radioactive material has activity `A_(0)`. The solution is kept in a container and is diluted by adding water at a constant role of 100ml/sec. From a small hole in the container 20ml/sec of solution is taken out simultaneously. find the activity of the 100ml solution that is taken out in 5sec. Assume that the half life of radioactive material is very large and that the solution alwyas remains homogeneous.

Answer

`A_(0)[1-((5)/(7))^(1//4)]`