A piece of bone of an animal from a ruin is found to have $\;^{14}C\;$ activity of 12 disintegrations per minute per gm of its carbon content .The $\;^{14}C\;$ activity of a living animal is 16 disintegrations per minute per gm .How long ago nearly did the animal die ? (Given half life of $\;^{14}C\;$ is $\;t_{\large\frac{1}{2}}\;$=5760 years)