During the testing process for some pharmaceuticals, the drug is tagged with a radioactive material. This way researchers can determine if the phamaceutical is going to other parts of the body than the intended target and what effect it has on the non$-$target areas. By adding this radioactive tag to the pharmaceutical, researchers can pinpoint all parts of the body and the concentration that accumulates in non$-$target areas.

One possible such tag is technetium$-99,{?}^{99}T$c$,$ which has a half$-$life of $6\mathrm{.}05$ hours.

How many ${?}^{99}Tc$ nuclei are required to give an activity of $1\mathrm{.}6Cl?$

$N=$ nuclei

What is the decay constant for this isotope?

$-$ hour ${?}^{-1}$

Suppose the drug containing the amount of ${?}^{99}$ Tc calculated in part $(1),$ were injected into the patient $1\mathrm{.}3$ hours after it was prepared, what would its activity be at that time?

$R=Ci$