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At time = 0, there are 8000 grams of a radioactive material present.
The half-life of the element is 18 years. In how many years will there be 335 grams remaining?
Round your answer to the nearest 0.01 years.
Thank you for any and all help to this equation :)
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Starting mass is 8000 grams and half-life period is 18 years.
It tells us, that the exponential decay law formula is
m(t) = ,
where t is the time in years, and m(t) is the remaining mass.
They want you determine t from this equation
335 = .
Divide both sides by 8000
= , or 0.041875 = .
Take logarithm base 10 of both sides and use properties of logarithms
log(0.041875) = .
It gives you
t = = use your calculator = 82.4 years (rounded). ANSWER
Solved.
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On radioactive decay, see the lesson
- Radioactive decay problems
in this site.
You will find many similar (and different) solved problems there.