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An initial sample of 502 g of a radioactive substance decays according to the function Alt)
where t is given in years.
502e -0.033t
(a) How many grams of the substance will remain after 68 years? Round your answer to one decimal place.
(b) What is the half-life of the substance? Round your answer to one decimal place.
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Answer :

Answer:

A = 502 * e^-(.033 * 68)     amount left after 68 rears

A = 502 e^-2.244 = 53.2 grams    after 68 years

A2 = 502 e^-(.033 * T)    = 251 where T is time for 1 half-life

ln (1/2) = -(.033 * T)

T = -.693 / -.033 = 21.0 years       for the half-life

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