Carbon14; Half-life
Radioactive decay
Organisms of animals and plants contain two types of carbons: carbon-12 and carbon-14.
After the death of organisms, the amount of carbon-12 remaines intact, but the amount of carbon-14 decreases slowly.
Comparison between the amount of carbon-12 and the carbon-14 allows to estimate the time elapsed after the death of the creature.
The amount of carbon-14 decreases to half in 5730 years. Half-life.
A fossil of an animal was found, it has 30% of carbon-14.
How many years have passed after its death?
