document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1208600>Question 1208600</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Bismuth-210 is an isotope that radioactively decays by about 13% each day, meaning 13% of the remaining Bismuth-210 transforms into another atom (polonium-210 in this case) each day. If you begin with 215 mg of Bismuth-210, how much remains after 7 days?\r<BR>\n" );
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document.write( "After 7 days, mg of Bismouth-210 remains.<BR>\n" );
document.write( "Round your answer to the nearest hundredth as needed.<BR>\n" );
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document.write( "Answer: <font color=red>81.11 mg</font>\r<BR>\n" );
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document.write( "Work Shown<BR>\n" );
document.write( "P = 215 mg is the starting amount<BR>\n" );
document.write( "r = 0.13 is the decimal form of the decay rate<BR>\n" );
document.write( "t = 7 days<BR>\n" );
document.write( "A = P*(1-r)^t  ............... exponential decay equation<BR>\n" );
document.write( "A = 215*(1-0.13)^7<BR>\n" );
document.write( "A = 81.109780898733<BR>\n" );
document.write( "A = <font color=red>81.11 mg</font>\r<BR>\n" );
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document.write( "The 210 is never used since it's part of the name, rather than an amount. <BR>\n" );
document.write( "Some teachers love to place red herrings to distract students.<BR>\n" );
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