Radioactive dating: half life, continued

The tutor continues about the phenomenon of half life and one of its well-known applications.

In my post from yesterday I introduced the topic of carbon dating and the principles that make it feasible. Today I’ll give a few more technical details to facilitate its mathematical use.

Example: A sample taken from a mammoth bone is found to contain 17% of the radioactivity of a freshly dead bone. Estimate the time of the mammoth’s death.


First, convert the percent to a decimal: 17%=0.17

The general formula for time since death, t, is

t=5730*(log(decimal remaining)/(log0.5))

We plug our decimal remaining, 0.17, into the formula:

t=5730*(log(0.17)/log(0.5))=14648 years

By the reckoning of the carbon dating process, the mammoth died 14648 years ago.

Incidentally, the radioactive form of carbon is carbon-14, whereas the (predominant) stable form is carbon-12:)

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.

Tagged with: ,

Leave a Reply