document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1128753>Question 1128753</A>: <I><SPAN STYLE=\"word-break: break-all;\"> The half-life of Erbium-171 is 7.5 hours. What is the hourly decay rate? Express the result to four decimal places.  </SPAN>\n" );
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document.write( "Let x be the fraction remaining after one hour.  Then, since the half-life is 7.5 hours,<br><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x%5E7.5+=+0.5 ALIGN=MIDDLE  ALT=\"x%5E7.5+=+0.5\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=x+=+%280.5%29%5E%281%2F7.5%29+=+0.9117 ALIGN=MIDDLE  ALT=\"x+=+%280.5%29%5E%281%2F7.5%29+=+0.9117\"   DISABLED_style= \"max-width:90%; height:auto;\" > to 4 decimal places.<br><BR>\n" );
document.write( "The amount remaining decreases by a factor of 0.9117 per hour.  That means the fraction that remains at the end of each hour is<br><BR>\n" );
document.write( "1-0.9117 = 0.0883<br><BR>\n" );
document.write( "I don't know which of those two numbers is your definition of \"hourly decay rate\". </SPAN>\n" );
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