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Math Help - Radioactive Decay

  1. #1
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    Radioactive Decay

    The strength of a radioactive substance decreases 50% in a 30-day period. How long will it take for the radioactivity to decrease to 1% of its initial value?
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  2. #2
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    The standard formula for radioactive decay, as you know, is N(t)=N_02^{-t/h}, where N_0 is the initial amount, t is the time elapsed, and h is the half-life (with h and t being measured in consistent units). So for the material to reach 1% of its initial value, \frac{N}{N_0}=.01. Therefore, simply isolate t in the following equation: .01=2^{-t/30}
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