how old is a mammoth's tusk if there is only 25 percent C-14 remaining in the sample?

a.5700 years
b.11400 years
c.17100 years
d.22800 years

Half disappeared in one half-life.

Half that remaining disappeared in the next half-life.

..what does that mean?

Knowing the half-life of C-14 would allow you to take twice the half-life.

From searching the Internet under "C-14 half life", I found that the half-life of Carbon 14 is 5730 years.

This should help a little more. Thanks for asking.

b.11400 years

B. 11400 years

5700

To determine the age of a mammoth's tusk, we can use the concept of radiocarbon dating. Radiocarbon dating is a method that uses the decay rate of the radioactive isotope carbon-14 (C-14) to estimate the age of organic materials.

The half-life of C-14 is approximately 5730 years. This means that after 5730 years, half of the original C-14 in a sample will have decayed. By measuring the remaining C-14 in a sample, we can estimate how long it has been since the organism died.

In this case, if there is only 25 percent C-14 remaining in the mammoth's tusk sample, we can assume that 75 percent of the initial C-14 has decayed. This decay corresponds to two half-lives since half of the remaining C-14 (50 percent) will decay after the first half-life, and half of the remaining 50 percent will decay after the second half-life.

Since each half-life is approximately 5730 years, the total time corresponds to twice that amount, which is approximately 11460 years. Therefore, the correct answer to the question is:

b. 11400 years