Half-lives of two radioactive elements A and B are 20 minutes and 40 minutes, respectively.Initially, the samples have equal number of nuclei. After 80 minutes, the ratio of decayed numbers of A and B nuclei will be:

Question

$\begin{array}{1 1}(1) 1:16 \\ (2) 4:1 \\(3) 1:4 \\ (4) 5:4 \end{array} $