Two radioactive substances $A$ and $B$ have decay constants $5 \lambda$ and $\lambda$ respectively. At $t = 0$, a sample has the same number of the two nuclei. The time taken for the ratio of the number of nuclei to become $\frac { 1 } { e ^ { 2 } }$ will be\\
(1) $\frac { 1 } { \lambda }$\\
(2) $\frac { 1 } { 2 \lambda }$\\
(3) $\frac { 2 } { \lambda }$\\
(4) $\frac { 1 } { 4 \lambda }$