Question 1030480
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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 155 grams of a radioactive isotope, how much will be left after 3 half-life's? 
Round to the nearest gram. 
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<pre>
It will be  {{{155/2}}}  after the first  half-life,
            {{{155/4}}}  after the second half-life,  and
            {{{155/8}}}  after the third  half-life.
</pre>