The half-life of a certain radioactive material is 75 days. An initial amount of the material has a mass of 381 kg. How do you write an exponential function that models the decay of this material and how much radioactive material remains after 15 days?

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Answer 1 · 2018-02-27T01:59:56

Half life:

#y=x*(1/2)^t# with #x# as the initial amount, #t# as #"time"/"half life"#, and #y# as the final amount. To find the answer, plug in the formula:

#y=381*(1/2)^(15/75)=>#

#y=381*0.87055056329=>#

#y=331.679764616#

The answer is approximately #331.68#