A fossilized animal that was killed by a volcano eruption has 12.5 percent of its original amount of carbon-14 remaining; this radioisotope has a half-life of 5730 years. How long ago did the volcano erupt?

34,380 years ago

22,920 years ago

17,190 years ago

9,168 years ago

Question

A fossilized animal that was killed by a volcano eruption has 12.5 percent of its original amount of carbon-14 remaining; this radioisotope has a half-life of 5730 years. How long ago did the volcano erupt?
		
34,380 years ago
		
22,920 years ago
		
17,190 years ago
		
9,168 years ago

kevin · Answer

Nt = 12.5% No
Nt/No = 12.5/100

Nt/No = (1/2)^(t / delta t)
12.5/100 = (1/2)^(t / 5730)
t = 17190