document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1196929>Question 1196929</A>: <I><SPAN STYLE=\"word-break: break-all;\"> M= log(E) - 11.8 / 1.5                       26<BR>\n" );
document.write( "1. A large earthquake is one that releases 10   ergs of energy. What is the magnitude (to the nearest hundredth) of such an earthquake on the Richter scale?<BR>\n" );
document.write( "2. How much energy (in ergs) is released in an 7.0 earthquake?    ?<BR>\n" );
document.write( "                                                                10  ergs\r<BR>\n" );
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document.write( "Thanks!<BR>\n" );
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document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #830106 by </B><A HREF=/tutors/aboutme.mpl?userid=Theo><B>Theo(13342)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Theo><IMG SRC=http://www.algebra.com/images/aboutme-small.gif BORDER=0 alt=\"About Me\" VALIGN=MIDDLE></A>&nbsp;<IMG SRC=http://www.algebra.com/cgi-bin/show-face.mpl?user=Theo><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=830106\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> your formula states that:<BR>\n" );
document.write( "M = log(E) - 11.8 / 1.5<BR>\n" );
document.write( "since log(E) = log(10^26) = 26, the formula becomes:<BR>\n" );
document.write( "M = 26 -  11.8 / 1.5<BR>\n" );
document.write( "that becomes:<BR>\n" );
document.write( "M = 18.13 which is unreasonable, since the richter scale doesn't go up that far.<BR>\n" );
document.write( "i believe the formula should be:<BR>\n" );
document.write( "M = (log(E) - 11.8) / 1.5<BR>\n" );
document.write( "the log(E) - 11.8 needs to be in parentheses to show that the whole expression is in the numerator.<BR>\n" );
document.write( "the formula then becomes:<BR>\n" );
document.write( "M = (26 - 11.8) / 1.5 = 9.466666......<BR>\n" );
document.write( "round to two decimal places to get M = 9.47<BR>\n" );
document.write( "that looks more reasonable.<BR>\n" );
document.write( "from M = (log(E) - 11.8) / 1.5, solve for log(E) to get:<BR>\n" );
document.write( "log(E) = 11.8 + 1.5 * M<BR>\n" );
document.write( "when M = 7, the formula becomes:<BR>\n" );
document.write( "log(E) = 11.8 + 1.5 * 7 which becomes:<BR>\n" );
document.write( "log(E) = 22.3<BR>\n" );
document.write( "this is true if and only if E = 10^22.3\r<BR>\n" );
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document.write( "your first answer is M = 9.47 rounded to 2 decimal places.<BR>\n" );
document.write( "your second answer is E = 10^22.3\r<BR>\n" );
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document.write( "let me know if you have any questions.<BR>\n" );
document.write( "theo\r<BR>\n" );
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