Question

If the half life of Carbon 14 is about 5,730 years, then a fossil that has 1/4 the normal proportion of Carbon 14 to Carbon 12 should be how old?

20,900

2,800

17,200

1,400

11,400

Answer 1

Last option is the right answer. The half life of C14 is given to be 5730 years, so half the amount of C14 would be left after 5730 years and after another half life of 5730 years (11460 years in total) the amount of C14 left in the fossil would be one-fourth (1/4) the original amount. One fourth amount of the C14 ​​​​​​would be left in the fossil after 2 half lives (of 5730 years) which is equivalent to 11460 years or approximately 11400 years.

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