Thehalf life of carbon is 5730 years. how many years would it take a 200 gram sample to Decay to only 25 G?
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When a half-life passes, only half of the mass of the sample stays. So to get to 25 g from 200, let's see how much half-lives will pass.
200÷2=100
100÷2=50
50÷2=25
The answer to that is 3 half-lives, or
3 × 5730 = 17190 years