Answer
a. 163 decays/min.
b. 0.43 decays/min.
Work Step by Step
The activity obeys the same decay equation as N(t).
a. Calculate the activity after 1000 years.
$$(184/min)2^{-1000yr/5730yr}=163~decays/min$$
b. Calculate the activity after 50000 years.
$$(184/min)2^{-50000yr/5730yr}=0.43~decays/min$$
