Initially two radioactive nucleus have same no of active nucleus their half life are 3 years and 4 years respectively after how many years, number of nucleus of one of the radioactive element is half the number of active nucleus of other radioactive element.

Explanation

Let `lambda_(1)=(ln2)/3` and `lambda_(2) =(ln2)/4`
`(N//2)/N=(N_(0)e^(-lambda_(1)t))/(N_(0)e^(-lambda_(2)t))`
t=12