document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1208725>Question 1208725</A>: <I><SPAN STYLE=\"word-break: break-all;\"> The loudness of a stereo speaker, measured in decibels, varies inversely as the square of the distance from the speaker. When you are 8 feet from the speaker, the loudness is 28 decibels. What is the loudness when you’re 4 feet from the speaker? </SPAN>\n" );
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document.write( "Answer: <font color=red>112 decibels</font>\r<BR>\n" );
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document.write( "Explanation\r<BR>\n" );
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document.write( "x = distance you are from the speaker <BR>\n" );
document.write( "y = decibel level\r<BR>\n" );
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document.write( "The loudness varies inversely as the square of the distance from the speaker.<BR>\n" );
document.write( "That gives us this equation<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=y+=+k%2F%28x%5E2%29 ALIGN=MIDDLE  ALT=\"y+=+k%2F%28x%5E2%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "As x gets bigger, y will get smaller, and vice versa.\r<BR>\n" );
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document.write( "Let's find k when x = 8 and y = 28<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=y+=+k%2F%28x%5E2%29 ALIGN=MIDDLE  ALT=\"y+=+k%2F%28x%5E2%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=28+=+k%2F%288%5E2%29 ALIGN=MIDDLE  ALT=\"28+=+k%2F%288%5E2%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=k+=+28%2A8%5E2 ALIGN=MIDDLE  ALT=\"k+=+28%2A8%5E2\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=k+=+1792 ALIGN=MIDDLE  ALT=\"k+=+1792\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Therefore the equation is <BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=y+=+1792%2F%28x%5E2%29 ALIGN=MIDDLE  ALT=\"y+=+1792%2F%28x%5E2%29\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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document.write( "If you are x = 4 feet from the speaker, then,<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=y+=+1792%2F%28x%5E2%29 ALIGN=MIDDLE  ALT=\"y+=+1792%2F%28x%5E2%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=y+=+1792%2F%284%5E2%29 ALIGN=MIDDLE  ALT=\"y+=+1792%2F%284%5E2%29\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=y+=+112 ALIGN=MIDDLE  ALT=\"y+=+112\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "<font color=red>112 decibels</font> is the final answer.\r<BR>\n" );
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document.write( "This level of loudness is somewhere between a loud night club (110 dB) and operating heavy equipment (120 dB).<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" src=\"https://www.osha.gov/sites/default/files/inline-images/fig3.gif\"><BR>\n" );
document.write( "Image Source:<BR>\n" );
document.write( "<a  rel=nofollow HREF=\"https://www.osha.gov/noise\">https://www.osha.gov/noise</a><BR>\n" );
document.write( "Scroll down to the \"Exposure & Controls\" subsection. <BR>\n" );
document.write( "Then click on \"how loud is too loud?\" to see the chart shown above.<BR>\n" );
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