Question

Determine the average life $U^{238}$ having $t_{1/2}=140$ days.

Answer 1

Half life period of $U^{238}{t}_{1/2}=140$ days.
Average life$=?$
$\tau =\frac{1}{\lambda }=\frac{t_{1/2}}{0.693}=\frac{140}{0.693}days$
$\tau =202.02$ days