document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=674913>Question 674913</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Could someone please help me with this stats problem I do not understand it at all.. Thanks in advance.\r<BR>\n" );
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document.write( "A researcher is interested in estimating the noise levels in decibels at area urban hospitals. She wants to be 99% confident that her estimate is correct.If the standard deviation is 4.09, how large a sample is needed to get the desired information to be accurate within 0.53 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 #419540 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=419540\">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 99% confident that her estimate is correct.If the standard deviation is 4.09, how large a sample is needed to get the desired information to be accurate within 0.53 decibels? <BR>\n" );
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document.write( "Since E = z*s/sqrt(n), <BR>\n" );
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document.write( "n = [z*s/E]^2<BR>\n" );
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document.write( "The z-value associated with 99% comfidence is invNorm(0.995) = 2.5758<BR>\n" );
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document.write( "Your Problem:<BR>\n" );
document.write( "n = [2.5758*4.09/0.53]^2 = 396 when rounded up.<BR>\n" );
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document.write( "Cheers,<BR>\n" );
document.write( "Stan H. </SPAN>\n" );
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