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The age of a wooden artifact was determined by carbon-14 dating. Three different measurements gave values of 6925, 4815, and 5485 years. Which is the best value to report for the age of this artifact?

A)   5700 years
B)   5740 years
C)   5741 years
D)   6000 years

I assumed that the best value to report was the average, which was 5741.667. but the answer is D) 6000 years. How do you get that?