Two radio isotopes A and B atomic weight X and Y are mixed in equal amount by weight. After \(20\) days, their weight ratio is found to be \(4 : 1\). Isotope A has a half-life of \(1\) day. The half-life of isotope B is:
1
\(1.11 \dfrac{Y}{X} \, \text{day}\)
2
\(0.11 \dfrac{X}{Y} \, \text{day}\)
3
\(0.6237 \, \text{day}\)
4
\(1.11 \, \text{day}\)