# The half life

The half-life of a radioactive isotope is the time it takes for a quantity of the isotope to be reduced to half its initial mass. Starting with 145 grams of a radioactive isotope, how much will be left after 3 half-lives?

Result

m3 =  18.125 g

#### Solution:

$m_{0}=145 \ \text{g} \ \\ \ \\ m_{3}=m_{0} \cdot \ 0.5^3=145 \cdot \ 0.5^3=\dfrac{ 145 }{ 8 }=18.125 \ \text{g}$

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