Question 1176084
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<pre>

Notice that  {{{(1/sqrt(2))*(1/sqrt(2))}}} = {{{1/2}}}.


It means that half-life of iodine-131 is two times 11.4 days,  or  2*11.4 = 22.8 days.    <U>ANSWER</U>
</pre>

Solved.


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To learn more on the subject, &nbsp;look into the lesson

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=https://www.algebra.com/algebra/homework/logarithm/Radioactive-decay-problems.lesson>Radioactive decay problems</A> 

in this site.


Also, &nbsp;you have this free of charge online textbook in ALGEBRA-I in this site

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=https://www.algebra.com/algebra/homework/quadratic/lessons/ALGEBRA-I-YOUR-ONLINE-TEXTBOOK.lesson>ALGEBRA-I - YOUR ONLINE TEXTBOOK</A>.


The referred lesson is the part of this online textbook under the topic "<U>Logarithms</U>".



Save the link to this online textbook together with its description


Free of charge online textbook in ALGEBRA-I
https://www.algebra.com/algebra/homework/quadratic/lessons/ALGEBRA-I-YOUR-ONLINE-TEXTBOOK.lesson


to your archive and use it when it is needed.



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By the way, &nbsp;the &nbsp;Internet sources give &nbsp;ANOTHER &nbsp;value for the &nbsp;Iodine-131 &nbsp;half-life: &nbsp;&nbsp;8 days.


So, &nbsp;your input data is &nbsp;INCORRECT.



See, &nbsp;for example, &nbsp;these sources


https://en.wikipedia.org/wiki/Iodine-131


https://www.radioactivity.eu.com/site/pages/Iodine_131.htm