Question

The half life of carbon 14 is 5,730 year suppose a fossil found with 20 percent as much of its carbon 14 as compared to a living sample how old is the fossil

3,235 years
32,346 years
1331 years
13,307 years

Answer 1

13,305 years

Explanation:

`A = A_02^{-(t)/(5730)}`

Since only 20% of the original C-14 is left, then
`A=0.2A_0`. We can then write

`0.2A_0=A_02^{-(t)/(5730)}`

Taking the log of both sides,

`\log 0.2 = \left(-(t)/(5730)\right)\log 2`

Solving for t,

`t = \frac{-(5730\:\text{years})\log 0.2}{\log 2}`

`\:\:\:\:\:\:\:= 13,305\:\text{years}`

Answer 2

13,307 I know because I do this type of math and I fell your pain but I asked someone else this question that’s why I don’t know step bye step but yeah hope this help