document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=632936>Question 632936</A>: <I><SPAN STYLE=\"word-break: break-all;\">  A researcher is interested in estimating the noise levels in decibels at area urban hospitals. She wants to be 90% confident that her estimate is correct.  If the standard deviation is 5.07, how large a sample is needed to get the desired information to be accurate within 0.66 decibels?  Show all work.  </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #398576 by </B><A HREF=/tutors/aboutme.mpl?userid=stanbon><B>stanbon(75887)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=stanbon><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/images/nopicture.jpg><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=398576\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> A researcher is interested in estimating the noise levels in decibels at area urban hospitals. She wants to be 90% confident that her estimate is correct. If the standard deviation is 5.07, how large a sample is needed to get the desired information to be accurate within 0.66 decibels? <BR>\n" );
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document.write( "E = z*s/sqrt(n)<BR>\n" );
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document.write( "So, n = [z*s/E)^2<BR>\n" );
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document.write( "n = [1.645*5.07/0.66]^2<BR>\n" );
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document.write( "n = 160 when rounded up<BR>\n" );
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document.write( "Cheers,<BR>\n" );
document.write( "Stan H. </SPAN>\n" );
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