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The mass m(t) remaining after t days from a 70 g sample of thorium-234 is given by the equation shown below.
m(t) = 70e-0.0274t

Find the half-life of thorium-234. (Round your answer to the nearest tenth.)

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you would be solving

35 = 70 e^-.0274t
.5 = e^-.0274t
-.0274t = ln(.5)
t = ln(.5)/-.0274
= 25.297

half life is appr 25.3 years

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