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A wooden artifact from an ancient tomb contains 70% of the carbon-14 that is present in living trees. How long ago was the artifact made? (The half-life of carbon-14 is 5730 years. Round your answer to the nearest whole number.)

And....

An infectious strain of bacteria increases in number at a relative growth rate of 200% per hour. When a certain critical number of bacteria are present in the bloodstream, a person becomes ill. If a single bacterium infects a person, the critical level is reached in 24 hours. How long will it take for the critical level to be reached if the same person is infected with 9 bacteria? (Round your answer to two decimal places.)

  • Math -

    the answer to ther second one is 22.85

  • Math -

    #1

    70%=0.7 (because70%/100%=0.7)
    The half-life 1/2=0.5

    Equation: 0.7=0.5^(t/5730)

    t=5730log0.7/log0.5=2949(years)

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