Answer:
The half life of an isotope is the time that an element take to reduce the half of the mass.
Explanation:
So for example,in the case of carbon 14, one gram takes 5730 years to reduce to 0.5 g, and then, it takes another 5730 years to be reduced to 0.250 g and so and so.
So depending the mass of the sample that you have, for example, a bone that weights 15 g, it will take 5730 years to have a mass of 7.5 g, and then 11, 460 years to have a mass of 3.75 g, and then 17,190 years to have a mass of 1.875 g, and so, and so.
Hope this info is useful.
Translation
The Doctor is giving an injection to the guy/boy
