A patient undergoing a heart scan is given a sample of fluorine- \(18\left({
}^{18} \mathrm{~F}\right)\). After \(4 \mathrm{hr}\), the radioactivity level in
the patient is \(44.1 \mathrm{MBq}\) (megabecquerel). After \(5 \mathrm{hr}\), the
radioactivity level drops to \(30.2 \mathrm{MBq}\). The radioactivity level
\(Q(t)\) can be approximated by \(Q(t)=Q_{0} e^{-k t},\) where \(t\) is the time in
hours after the initial dose \(Q_{0}\) is administered.
a. Determine the value of \(k\). Round to 4 decimal places.
b. Determine the initial dose, \(Q_{0}\). Round to the nearest whole unit.
c. Determine the radioactivity level after \(12 \mathrm{hr}\). Round to 1
decimal place.